Have you looked at all you error logs? What do they say, if anything.
On another note, since we can't see what you see, not much we can do to help. Your question is about as helpful as telling an automobile mechanic over the phone that your car is broke and asking what could be wrong?
The error log has the following:
SQL Server has encountered occurences of I/O requests taking longer than 15 seconds to complete on file g;|templog.ldf