Our NetXMS v2.0.2 server on Windows 2008 R2 stopped working today and kept crashing on startup. The event log showed
[ERROR] EXCEPTION 0xC0000005 (Access violation) at 0x00659F20 (crash dump was generated);
From the crash dump I found it was caused by nxcore!ScheduledMaintenance+0x150, which appears to have something to do with nodes that have been set to maintenance mode.

I checked the database and found that there were some entries in the scheduled_tasks table pointing to IDs of nodes that have been deleted meanwhile. Unfortunately, running "nxdbmgr check" did not clean these up, so I deleted them manually and the problem was gone.

Not sure if this is something already solved in a later version or not, but thought I'd let everyone know in any case!