China DOS Union

I still haven't been able to solve this problem. My C drive has Win2000 (FAT primary partition), and XP is installed in logical partition D. At the time of installation there was only one primary partition, C. Now as long as I convert XP's partition D into a primary partition, it won't boot... Whether I convert it or not, XP is still the 2nd partition. How can this be solved? Can someone help? Thanks...

Of course it can't boot, the boot files are all on the C drive.

I only converted it from a logical partition to a primary partition, and it still remains the 2nd partition. The active boot partition is still C and hasn't changed, so why won't it boot? The problem happens right when it's about to reach the desktop. At "Loading your personal settings," it gives this message: "A problem is preventing the activation code for this machine from being properly verified"; then it keeps looping between logging off and loading settings. Only if I restart manually and change it back to a logical partition does everything become OK again. I don't know where the problem is...