Hey there Amigo, welcome to Geeks To Go Forums.
Click start then run, type prefetch then press enter, click edit then select all, right click any file then click delete, confirm delete
Click start, all programmes, accessories, system tools to run disc clean up.
Click start then run, type sfc /scannow then press enter, you need the XP CD and Windows File Protection will show a blue onscreen progress bar, when the bar goes, reboot
Click start then run, type chkdsk /f /r then press enter, type Y to confirm for next boot, press enter then reboot.
Windows will appear to load normally then either the monitor will show progress or the screen will go blank, do not disturb this. This will take an hour or so before it gets to the desktop.
Try this, the problem details lead me to belive that windows system files may have been damaged when installing a new program. The solutions should work, let me know.