Had an issue this morning at a clients whereby a Vista machine wasn’t booting; particularly during login. After inspecting the logs, I noticed the SRTSPL.SYS file was causing the stop errors; this relates to Symantec Endpoint Protection. To fix;
1. Reboot the machine in safe mode.
2. Disable all SEP services on startup.
3. Reboot in normal mode and run a repair on the SEP install.