Welcome to the forums!
Before you get too stressed out 
, start by rebooting your Pearl. While the phone is on, remove the battery for 15-30 seconds, reinsert it and wait for your phone to reboot.
This may help resolve the problem. Note, there are no known viruses for BlackBerry, so chances are that it's just in need of a proper reboot.
Keep us posted.
Just in case I head off to bed before you are able to respond, here are a set of steps you can follow. Basically, what we're going to do is reload your phone's operating system. It's basically our last step here and if this doesn't work, we're likely looking at a hardware issue.
First off, since you already backed up your phone we don't need to worry about that right now.
Find your service provider from the following website and click on the link: http://na.blackberry.com/eng/support/downloads/dow
From the download site, select your phone model from the drop down menu. Download the most recent operating system to your computer and then install it to your computer. Once you've done that, follow the instructions I've written up here on how to reload your OS:
The key step here is Step 4. This will ensure that everything is wiped 100% off the phone.
Once you're done this, and before you do anything else (like reload your 3rd party applications and restore your data), see if the problem is still happening. If it is, I'd say that its 99.999999% certain the problem is a hardware issue (in which case, you'll need to go to your service provider for help). If the problem has cleared up, you can redownload any 3rd party apps (do not use any 3rd party application backups you may have on your computer (if you do)) and restore your data. If you want to be 100% certain that you don't have problems, do an advanced restore of your data where you only select the databases you absolutely need (e.g. Address Book, Calendar, Messages, etc). Leave as much off as possible.
Good luck and definitely keep me up to date on the progress. I'm going to be calling it a night now (it's almost 2am here), but I'll check the forums again in the morning some time. 
