I had a similar problem, i got to the desktop, with no icons or a start menu. what happened was Internet Download accelerator had told me about a corrupt registry ( or something around that) i just ignored it and shut my comp down when i went to sleep. that same thing happened to me when i booted it up. the only fix i could find was to put the xp cd in and reinstall windows over my existing copy ( saving all my data, except fo the OS files) you should also try to get into safe mode, but i think i tried it and it froze when loading the mup.sys file. if you can't get to safe mode, or that doesn't help solve your problem, try repairing windows like what i did. you may have to redownload all the up dates, but that is better than reformatting and losing everything.
AMD Athlon XP 2500+@ 200x11 - EPoX 8rda3I - Thermaltake 420watt silent PSU - 2x512MB PNY PC3200(DualChannel) - TT HSF - PNY 5900SE, 128MB DDR, 256-bit - - Toshiba SD-R5002: DVD-RW - NEC DVD-RW - 2 Antec 80mm fans - 1 Delta 92mm fan - 1 Antec 120mm fan- 1 TT 120mm fan - Windows XP Pro - WD special edition 80GB 7200 RPM- Seagate 80GB 7200 RPM 8MB cache - Onboard Sound - Onboard Ethernet
ACER Travel Mmate 4000LCi - Intel Pentium M 710 - 15\" XGA TFT - 512MB DDR333 - 40 GB HD - DVD-rom/CD-RW Drive - WLAN 802.11b/g - Winxp Home - Intel Extreme Graphics - Average Battery Life: 4-5 hours - 6.4 lbs