Abnormal activity on my W2k/E2K Server

I am running a W2K Server and Exchange 2000 Server.The Exchange server stops once in a while and it has to be re-started. This is because of many temporary files that does not get erased automatically, and they keep on piling and filling my c: drive(about 400 tmps are generated every day).
The Active directory log files are also generated at an alarming state (about 600 are generated daily).

When I stop the Information Store all the tmp files are cleared from the Winnt directory, showingthat they are being used by the IS service. Any ideas on what could be causing this???