Windows freezing on file open/close - help!

Hi,

I recently built a new system and have a problem that I think is software related. Sometimes when I open or close the file the screen freezes for about 10 seconds, most or all of the desktop icons disappear but the place holders remain. After this time the system refreshes quickly. The mouse works without problem throughout but the folders and icons are frozen. It can happen at any point while the computer is on.

The issue seems to be getting worse and the system seems to hang for slightly longer each time. This also happens on my laptop but on it tends to be for a brief moment on the laptop, with this new computer it lasts much longer and the new computer is much faster.

The computer is fast and has lots of memory so I cant understand why this is happening. Windows updates are all up-to-date. The hard drive is defragmented. I have tried the following in order to try and solve the problem but so far without success:

Updating all the drivers (inc. video and Bios)
Checking the windows error log – nothing listed for when the problem occurs
Ran chkdsk on my hard drive – Samsungs diagnostic software wont run
Changed the sata ports where the hard drive is plugged in
Disabled unnecessary startup programs
Disabled unnecessary drivers e.g. Jmicron IDE controller
Changing video card settings to performance
Reducing windows paging file
Changed the registry DisablePagingExecutive to 1

The spec is as follows:

Core 2 Quad Q6600 cpu (2.4GHz quad core)
Asus EN8600GT Silent video card (256mb passive cooling)
Asus P5K-E/Wi-fi motherboard
Samsung HD501LJ Hard Drive (SATA)
Asus 1814BLW DVD-ROM (SATA)
Transcend DDR2-800 RAM (1GB x 2 = 2GB total)

Relevant software being run at start-up:

Windows XP SP2 with all current updates
Zonealarm pro firewall (windows firewall disabled)
Webroot Spysweeper
BitDefender standard antivirus
Timeleft – desktop clock
Secondcopy – back-up software – set to run manually


Please help if you can, its very annoying! Thanks in advance.