That's interesting.  After downloading and installing openacs 4.6 and dotlrn-1-0, I can consistently crash (segfault) aolserver by selecting the "my portal" link in dotlrn.  The backtrace is very cryptic, but it shows that aolserver was executing in the regexp code for tcl8.3.  I've tried unloading all unecessary modules without any change.  I'm using aolserver3.3+ad13 on solaris 2.8.

What version of aolserver are you using?  Have you tried loading the core file to see where the crash occured?