The error message "Unable to update the session management database" may be due to memory issues.Try upgrading to the version 8.0.3.10 as most of the issues experienced before have been fixed in this version.
please send me the "show tech" and the "show memory detail" output when the issue happens next time. If the issue is caused by some memory problems, hopefully we wold see it from these outputs.
The workaround is to turn off the WebVPN compression for both the
svc and http as well with the command "no compression all".