Blue screen with error message 0x00000024 on winXP pro

hi there.
i have win xp pro SP2 on a toshiba 2410 petium 4 1.8GHz, 1024mb RAM, 80Gb HDD, etc. running with AVAST 4 Pro. ive had the SP2 for ages and also had avast alos for ages, always been good, did the update this morning and all was well, even did reboot at one point and all ok… no problems until alte today when i run a thorough scan of HDD, and all was well, then during the scanning i opened a pdf file… and was reading it when the blue screen appeared and did a dump…
after that the computer tried to restart, with the safemode and and other option screen… when i chose any of the options like normal start or use the last known good configuration etc, the normal win xp splash screen appears then, it reboots back to the same safemode option screen again… this keeps going on and on…
ive tried a floppy but cant seem to do more than do a check of the hdd sectors. cant seem to do a scandisk or… chkdsk of c:
simpy cant find the hdd… except when using… the analyze sectors… etc…
i must confess im away and not at home (im overseas) where all my goodies are, recovery disks etc. so im using a dell recovery disk… and my computer is toshiba… which is maybe why some parts are not accessible for my system…

anyone got some ideas…

i have been onto the microsoft website and read loads of the knowledge base articles… and a few conerning this particualr error code…

but nothing useful yet…

HelP…???

What did you update? avast! or Windows?
Can you remember which updates of Windows did you install?

Please check the folder \data\log
Are there any files called unpXXXX there (where XXXX is a random number)?
If so, send them to vlk@avast.com
They may contain more information about the problem (maybe a link to this thread).

if blue screen appears, please send some of the latest minidump files (from \Windows\Minidump folder) to vlk@avast.com or me - unpXXX are only created when our application crashed (and not whole computer to blue screen - as in your case). Thanks.

0x24 error means: NTFS_FILE_SYSTEM
description here: http://www.microsoft.com/resources/documentation/Windows/XP/all/reskit/en-us/Default.asp?url=/resources/documentation/Windows/XP/all/reskit/en-us/prmd_stp_swhw.asp

caused by a bug in a driver or hdd problem (try chkdsk with the parameters they suggested).