debug reports random causes

14 crashes on 10/29/06, various debug causes including savrt.sys, memory_corruption, win32k.sys, ntoskernl.exe and classpnp.sys. I uninstalled NAV 2006. 2 crashes on 10/30/06, debug causes: savrt.sys and win32k.sys. No crashes on 10/31/06. Installed NAV 2007 11/1/06, 4 crashes, debug causes: srtsp.sys twice, win32k.sys and ntoskrnl.exe. I have attached the last 4 minidumps and debugs w/analyses. Obviously I could uninstall NAV 2007, but I'm not totally conviced it's just that. Help, please. Thanks!