searching where all drive icons should be.

3 times in last 3 weeks. Likely Software or Hardware Problem or ??

XP SP!+++/80G West.DigitalHD/512 RAM/P4(C: Drive)/Intel MB 865GBFL/3.0Ghz.
AVG 7.5 AV & 7.5 AS, BoClean DISABLED @ startup, AAW SE 1.06, Spybot HE1.5_17 Beta, w/Resident active, CCleaner.
Sea Monkey exclusive browsing.Cable Modem & D-Link Router.

ALL up to date, shows clear on all scans incl. AVG rootkit & Blacklight.Defragged, cleaned, running cool (temp). No unusual noises from box. 3 years old & used extensively. Updated to 550 watt dual fan PS(1/2Yr ago).

Tale of Woe....

The 3 occasions this has happened have been after leaving net (2 times C-Net forums & 1 time from a travel board, in each case at least 1 hour online).

Symptoms: After disabling LAN connection, desktop is only somewhat responsive, mouse clicks on icons either do nothing but highlight or gives "Hourglass"wait signal for System functions CAD,Sys Restore, 3rd party programs icons etc.

Clicking(mouse) on "start" no reaction. Manual turn on/off power button also no reaction. Desktop appears normal.
Double left click on "My Computer" brings up a "flashlight seeking in the dark" but nothing else where drives should be shown.

Only action effective is pushing the Hard Drive Button on front which reboots to last good config (?) This brings machine back to normal operation.

After this I can & do run sys restore &/or SFC or Checkdisk /R (most often as I fear bad area on HD could be culprit). Of course all scans are run in case it's some attack on net but in each case basically only safe, reputable sites have been visited and nothing at all unusual found.

Weirdly, Event Viewer shows no errors or warnings in then current time frame & the winlogon when viewed shows nothing unusual from checkdisk /R as far as I can determine. Defrag shows less than 1 frag per file. System averages 88% free.

Have no REAL reason to believe S&D Halloween Ed. is at fault,( I noticed the update progress bar doesn't work in this edition) BUT it is the ONLY BETA program on machine & the timing (3 weeks) seems suspiciously close to latest S&D HE. NEVER saw this before.

Anyone else seeing similar??

Mystery to me...what think Ye?? Thanks In Advance!! Sandy