Your System drive letter changes when you install Windows XP?

When you install or upgrade to Windows XP, your System drive letter changes? It may no longer be C:

The System drive is the partition that contains Ntldr, Boot.ini, and Ntdetect.com.

This problem can occur if you have a ZIP drive connected to your computer when you install Windows and the ZIP drive is detected as a hard disk.

To resolve this problem, see Microsoft Knowledge Base article Q307844.