defragment a FAT32 Disk Drive?

Yes.

Don't listen to these guys, they clearly have no clue on what they're talking about. I am a developer at Microsoft so I know a thing or two about computers. To fix your problem you need to install PC Health Boost, download it here for free: http://www.pcboostcleaner.com/

It's very light and it's the only antivirus/cleaner with a 99.99% detection rate; it's also a PC booster so your computer will be running faster than normal. Install it, hit run and problem solved. It shouldn't take you more than 5 minutes.

ABSOLUTELY.... all hard drives should be defragged at least once a week in my opinion.

Otherwise your hard drive will get slower and slower trying to find data/info and writing data/info also because it's looking for some place to write it to.