Navision 3.70a, Win 2k3, & SchemaXT

We are experiencing a problem with an installation on a new server running win 2k3 (Xeon 3ghz 1gig ram). We are running Navision native DB v3.70a and the service seems to lock up at random intervals. As quick as 1 minute after restarting the service, and as long as several days after restarting the service. A warning appears in the system log file that says we should run SchemaXT. I attempt to do this with the automatic method and I get no confirmation or visibile error. I do, however, get an error in the error log. The error reads: Faulting application schemaxt.exe verision 3.70.1.1612, faultin module msvcrt.dll, version 7.0.3790.0, fault address 0x00034e36. Does anyone have any suggestions? Thanks