Unable to turn off pc without disconnecting power supply

I returned to find a blank monitor and the HDD light on the front of my PC blinking sporadically. Also no period of pressing or holding the power button would turn off or restart the system. I ended up having to unplug the power supply to shut it down. Whenever I plug the power supply in again I am met with the same issue. No screen a continuously blinking HDD light and the inability to turn off or restart using the power button. Case, Video Card, and Heat sink fans are still being powered/operating.

New components I have added in the past 3 months are:

-Kingston 512mb ram
-Gecube ATI Radeon 9250 PCI
-Western Digital 160gb HDD


So far I have tried this and started system up again:

-Removing new ram installed. (Same results)
-Disconnecting IDE cables to optical devices and FDD (Same results)
-Disconnecting power and IDE cables to Hard Drives (Same results)


Additional information that may be useful is that for the past month at least once every week to two weeks my computer would make a single beep. I took this as nothing since this was not during start up and felt it did not signify anything. Also for the past month about once a week my monitor would go blank for a second then return back to the desktop.

Emachine T2385:

Phoneix Bios (I think)
Bestec 250 watt power supply
Gecube 9250 ATI Radeon
Western Digital 160 HDD
Western Digital 80 HDD
Kingston 512 ram
Crucial 512 ram
P4 Northwood Celeron 2.30

Number of possibilities. Try clearing the CMOS, instructions should be in the manual that came with the computer. Try a Windows repair off the CD if you have the CD. Most recovery disks will wipe out the hdd and do a complete install, so you'd have to back up your data before doing this, Repair shouldn't affect you data but always a good idea to back it up. Try another PSU could be going bad and 250w is really weak.