USB Stick works in XP but not Seven

Hi,

got problems with my USB sticks. I have 2 Platinum 16gb sticks. I run a dual boot system with XP an win7. If I plug the sticks when I'm running seven, seven says the volumes have to be formated.
When I plug them while I'm running XP everything is fine. No problems...

Same system. Different OS...

The sticks are new. I tried to format them, but after I plug them into my Pioneer CDJs. The same behaviour appears.

Are they formatted in NTFS or FAT32?

When I put my all sticks into NTFS my compatibility problems cleared up.

If I recall correctly, I made the change from one to the other in Command Prompt.

They are in FAT32. HM, maybe thats the problem even if it shouldn't be. Do I have to format them or is it possible to leave the data on there and change to NTFS?