By any chance, are you using Vodafone for access in Turkey? Someone asked a similar question in a Vodafone forum. You may want to join the forum and communicate with this person to see if they resolved the issue. The link is below: Blackberry Storm keeps re booting only in turkey - Vodafone eForum
From my experience and research, I have read that getting the Storm to work in that area normally require unlocking and the use of a sim card from a local carrier. For Turkey that would be Avea, Turkcell, and Vodafone.
I think my Saudi Arabian friend travels into Turkey with his Storm. If your BBM functions I can slide you his PIN to see if he had any issues when traveling there with his Storm.