Memory being full causing it you say? I'll try to see if I can find out how much it's using at any one time and keep track of it. How would I check the memory usage. Is there an easy way?

I don't keep messages (emails) on my BB. I usually delete them within a day, so at any given time I have no more than 25 or so emails on my device.

If it helps, here's what I have loaded on my BB (extras - stuff I put on there in addition to what comes from the factory):
- blackberry maps
- google maps
- yahoo messenger (always logged out when the reboots happened)
- Wave icon theme
- Gmail application from google

Like I said, I know for sure it's rebooting even if I don't see it happen because my enterprise messenger would not be logged in if it hadn't rebooted. Also, if I see my BB is locked and it's been less than an hour since I looked at it last, I know it rebooted because it won't lock otherwise until the 1 hour time expires for when I told it to automatically lock.