Pretty much as the title suggested:

For no apparently reason, my Blackberry (7200 series) went to the "hourglass" symbol for a few minutes. When services were restored, all my email between August 10th and Yesterday had been deleted.

I am using the BIS v2 service and have set the BB to delete on Handheld only, although I'm not sure how relevant this info will prove to be?

Anyone have any insight?

Some form of memory leak I would imagine. Was your BB connected to your pc? It also sounds almost like it reverted back to a backup? What version of the software are you using?