Windows 7: Windows partition changed itself to D, failing to boot

Hi guys!

I have a Windows 7 x64 installed on a single disk with 4 partitions:
- The default 100MB invisible boot partition
- 150GB system partition C:
- 2x 850GB partitions D: and E:.

After experimenting with another disk (an SSD planned to be used as a working disk for video editing, but that's another sad story), the drive letters got messed up. The invisible 100MB partition took the C: letter, so all the other partitions moved for one letter, preventing a normal boot!

The Startup Repair that keeps popping up is failing to fix the problem by itself. Using the DISKPART command from the Advanced mode I removed the letter from the 100MB partition and reassigned the other partitions to their original letters, but on the first boot, the 100MB partition reappears, messing up everything!



Please, guys, is there a solutuon that does not involve a complete OS reinstallation?

Thanks!
Jonnie

Do a Strartup Repair:
Startup Repair
Note: You may need to do startup repair 3 to 4 times.
Startup Repair - Run 3 Separate Times

Thank you for the quick answer. I tried it, but it did not help...

I set the 150GB partition to active, though (it was inactive), and that caused the System disk appearing properly as C:. However, now the Reserved 100MB partition became D... I ran the startup recovery, but it still fails with no explanation. Just "unable to do the automatic recovery".

Reserved 100 MB partition should be the active partition.

Remove the Drive letter from SysReserved using free Partition Wizard
bootable CD, make sure it's marked Active, then from Disk tab select "Rebuild MBR."

If this fails run Startup Repair from DVD or REpair CD repeatedly.

Next boot Paragon Rescue CD which is the tool used to change back a System Drive letter that accidentally slips: Paragon rescue disk; change drive letter; recover data

Boot the Paragon cd - select Normal Mode , then Boot Corrector.

Correct drive letters in the system registry.