Sometimes Win XP Welcome screen hangs

I recently assembled my new system and did almost exactly the same installation process as I have done for my old system many times (except drivers for my new hardware). But now I experience random freezes at the blue Welcome screen.
If logon process goes normally, there are three stages I have noticed:
1- right after boot screen disappears and welcome screen appears there is some HDD activity
2-hdd activity stops for 1 or 2 seconds
3-hdd activity starts again

But one time out of 10 or 20 everything freezes at the stage 2. I can move the mouse, turn NumLock on/off on my keboard, but I cannot select any user name to log on they are frozen. I tried using Windows Logo key + U (usually this brings up Utility Manager for Accessibilty) but it does not work.
So the only choice is do a hard reset.

I did not find any errors in Event Viewer or any hardware conflicts. I have tried to use /bootlog option in boot.ini file but it logs only drivers and nothing about what happens at logon stage.
Any ideas? Or maybe a good utility which can log everything that happens when my pc boots up and after that until Desktop appears?
Thanks

My PC Info:
MOBO: ASUS P5PL2/C, CPU: P4 Cedar Mill 3.2GHz HT, RAM: 512MB Kingmax, Video: MSI Radeon RX300HM 256 HyperMemory, Sound: Creative SB Live! 5.1 Digital, HDD: ExcelStor J880, DVD-RAM/RW: TSSTcorp SH-S182M, PSU: Codegen 400W, OS: Windows XP SP2

 

You could try the /sos switch in the boot.ini (it might do the same thing as /bootlog, but what the heck...); it will hopefully show what the problem is. It could also be flakey RAM (run a diagnostic). Maybe check w/ Asus for a possible patch or fix for the problem: a driver update or new BIOS. Maybe run a diag on the HD also....