Computer won't Boot after Reinstalling Windows XP on a Linux/Windows Dual Boot System: Another Windows XP Bug

Using a dual boot system is sometimes a little tedious. In particular since the windows installer is keen to screw up any operating systems that are installed on your hard drive besides windows. Here is what happened to me after I had to re install a broken windows instatllation on a dual boot system.

If you mess around too much with windows it will sooner or later cease to boot. Usually it is sufficient to boot with the windows installation disk and to choose the repair installation.
However, in my case repair installation did not help, and I had to do a clean install. Yet, after finishing the Windows XP SP 2 installation my computer was completely screwed up. After the Windows XP isntall it bacame impossible to boot any operating system, neither the old windows, the old linux nor the new windows. Usually in this cases it helps to boot the computer from a rescue boot disk and then boot the required partition. But in this case it didnt help at all. Also the repair utility featured on the Linux installation disk did not help at all. So I thought my harddrive would be lost.

However, after taking a look at the master boot record (MBR) of the hard drive I figured out what the problem was:

The windows xp installer flagged both partitions of my harddrive as active after the clean install. Because after the linux installation I used GRUB as a boot loader, the linux partition was set as active in the MBR.
So the Windows XP installer set the windwos partition as the active partition and leaving the active flag for the linux partition in place. Thus, after finishing the Windows XP reinstallation my MBR ended up with two partitions flaged as active. This is a condition which should never be present in a master boot record.
To fix the MPR you have to edit it to flag the only that partition active you want to boot from, e.g. the partition containig the GRUB boot-loader. Caution: Never use the fixmbr command from the recovery console to fix the MBR. This command will overwrite your partition table and screw up your entire hard drive.
I consider this as another nasty Windows XP bug. Considering the Microsoft marketing strategy it is conseivable that Microsoft intentionally put this bug into their installation routine to deliberately screw up systems that hold other than microsoft operating systems on their harddrive.