Yep. Disconnect any external drives; anything whatsoever. No pen drives, no external hard drives, nothing. Then remove the battery (as you've pointed out, red-dawg) and let that puppy sit for a few minutes (obviously with power unplugged as well).
Then......replace the battery, plug in the a/c adapter, and boot up. As it is booting, hit F1 to get to the system BIOS. Look at how your laptop is setup in terms of boot devices; in other words, in what order does it look at devices to boot from. I'd suggest you set it to look at your CD or DVD player first, then your hard drive (floppy before that if you have one). Save and exit BIOS, continue booting.
If you are still having problems, power down, insert your Windows XP CD, and boot from it........have it run a "repair" instead of a "clean" install.