Slow computer won't complete Disk Defrag

the disk could be failing. backup important data and run chkdsk.
http://answers.microsoft.com/en-us/windows/forum/windows_7-performance/using-windows-7-how-do-i-run-chkdsk/a68b3e4d-1a42-e011-9767-d8d385dcbb12

Your first mistake was to put anti spyware and avast in the system.
Free downloads like this spell disaster. Avoid them always.
Use only a professional all in one security system, such as Kaspersky, Norton, Panda, etc...
Loading two different security systems causes compatibility issues, and system conflicts. You just found out about that...

Delete ALL free downloads and junk programs that you installed from the internet...IF you can.
Turn OFF all security and firewall.
THEN do a defrag.

If you managed to do that, then try this:
Click Start, Click Control Panel,
Look at the top of the window, in the path bar you see “control panel >”
Click on “>” (in the path bar) now click on “all control panel options.”
(This will open up all the hidden controls available)
Click Power Options
click on the arrow to “show other plans”
Check the Box that says "high performance"
Click (in high performance) "change plan settings"
Turn off display: set to NEVER
Put the computer to sleep: set to NEVER
Click: Change advanced plan settings
Scroll down the list: Click on the + signs to expand the choices for each item on the list.
Require a password on wake up: set to NO
Hard disk: turn off the hard disk: set to NEVER
Wireless adapter settings:
Sleep: set to NEVER
Allow Hybrid sleep: set to NEVER
Hibernate after: set to NEVER
Allow wake timers: set to disable
USB settings:
USB selective suspend setting: set to NEVER
Power Buttons and lid:
Power button action: Setting: set to shut down
Sleep Button Action: set to: do nothing
PCI Express:
Link State Power Management, Setting: OFF
Processor Power Management: Minimum state (set to) 7%

System Cooling Policy: setting: Active
Maximum State (set to) 100%
Display
Turn off display after: setting: NEVER (turning off display automatically can cause freezing also)
Turn off the monitor power manually, when you want it off. Don’t use the auto monitor turn off.
Multimedia Settings:
When Sharing Media: Setting: Prevent idling to sleep
When Playing Video: Setting: Optimize Video
Click APPLY
Click OK

Open the bios set up and make sure "cool and quiet" is OFF. (AMD)
If there is a power saver or a "quiet mode" in the bios, shut it off...
There may be a performance setting in the bios setup you have...make sure it's cranked up to max.
in the bios, see that the allocation for video, if available, is maxed.

Now open the hardware manager profiles...
click start
click computer
click system properties
click device manager
double click on mice and other pointing devices
right click on HID compliant mouse
left click on properties
click on the power management tab
UN-check the box that says: "allow the computer to turn off this device to save power." (there is now NO check mark in this box)
click OK

Now repeat this procedure for all mice, monitors, keyboards, and ALL USB ports on the device manager list.

You must open ALL the devices one at a time, as above, and turn off the power saver, for each device.

NOW turn all the security back ON. NOW open your security antivirus. Make sure the antivirus is set to "gaming mode." Or "multimedia mode."
This prevents the security updating from interrupting your game / multimedia priority.
IF the security does not have "gaming mode" or "multimedia mode" get different security.
IF you are using "free" security downloaded from the internet, get rid of it NOW.
Use ONLY professional all in one security. DO NOT load multiple mismatched security programs, which conflict with each other.
DO NOT load free tools into your system such as: "driver sweeper" or any of that "free" goofy stuff.

what anti spyware program? how much room left on drive?

I stopped reading right there. While you are correct that one should not have two antivirus applications on one PC, there is nothing wrong with Avast as an antivirus.
And we do not know specifically what the OP meant by "antispyware".

chkdsk

avast has had plenty reported issues, don't you read tom's hardware? I would never install that stuff.
hahahahahahahahah!

How much of the disk is free ? This is common when there's not enough empty space

SuperAntiSpyware ius something I'd drop ..... although it will NOT cause any problems with Avast as SAS includes no real time scanning feature.

http://en.wikipedia.org/wiki/Superantispyware

It is specifically designed to be compatible with other security applications, and therefore can be used even when those other applications are incompatible with anti-spyware products, such as Kaspersky....SUPERAntiSpyware received a "POOR" rating from PC Magazine, which complained that it had no real-time protection and the lowest detection rate and lowest score in a malware removal test

Click to expand...

The can not use two antivirus programs mantra is a fallacy. What is true is that it is unwise to use two "active" anti virus programs at the same time; they will interfere with one another. However, it is totally safe and quite prudent to use one program as an active scanner and then have a second program run periodic (passive) scans on demand or on a schedule. This is "policy" on most forums that I have managed or worked on which maintain online libraries going back to the late 1980s. Every file must be scanned by at least 2 AV programs before getting released for public consumption.

still don't know the room left on the drive. this is the 3rd time asking.