I have seen on many occasions that after trying to install software or a device, something in Windows may become corrupt and sometimes to the point where Windows will not boot. If after trying to restore to a last known good configuration you still cannot boot. You can try a last ditch effort at the Recovery Console. The Recovery Console will give you access to a DOS like environment where you can try to fix suspected problems. Here is how to install the Recovery Console:

1. Place your Windows XP CD into your CD-ROM drive
2. Go to Start>> Run. Type in: d:\i386\winnt32.exe /cmdcons (assuming D:\ is your CD-ROM Drive). Press Enter on your keyboard or click OK.

A Windows setup dialog box will now appear. Here, you can read about the Recovery Console option. After you're done reading, click YES to confirm the installation.