and welcome to the forum.
" i have ran a Hijackthis log, which did not find any spyware or malware "
I take it you know how to read a HJT scan ?
This is not sarcasm,but HJT logs can be extremely difficult to understand and playing with the scan results can render the machine in-operable or function incorrectly.
What happens if you disable Norton and its startup entry in MSCONFIG.
Also check for any services related to Symantec and stop these.
Now reboot....is the bootup quicker ?
Does the machine boot ok into safemode ?
You are relying on an error report that is saying SRTSP.SYS is at fault,disabling Norton and its services briefly will prove if the error report is correct.
No idea if you are using 2008 or 2009 Norton,but i believe there is a free upgrade to 2009 if using 2008.This may cure the SYS error.