Press the F8 key just before Windows starts and you should be presented with a number of options. The first to try is "last known good". If that does not work, see if safe mode does. If it does work, it would sound as if you could have a driver that's incorrect, corrupt or missing, a service that cannot load, etc. If that's the case, you need to start disabling startup processes until you find the culprit. It can be a tedious process.
Been having XP problems. System will start to boot, I see the blue bar going from side to side and it just stops. System will not get past this point and I have tried many, many times. I even left it overnight and it never goes past this point. So I purchased a new hard drive (WD 500GB SATA), installed it, put in the Win XP install disk. The install process goes fine till it says "Setup is starting windows" and it stalls there. Again I have tried several times and it will not get past this point. Tried resetting the BIOS and diff. memory config. and these were no help.
It appears to be system hardware as I have a new drive. I tried to overwrite/repair the old system disk with the problem above and it did the same thing, stalls at starting windows as above.
MB: Intel D102GGC2
Memory: 4 GB
OS trying to install: Win XP Pro
Hard Drive: WD model: WD5000AACS-00ZUB0