My HL2 was also crashing every time during a save or "loading.." with the infamous memory reference error.
Sanmeet's post at
http://www.moviecodec.com/topics/4097p7.html helped me to resolve the issue and play HalfLife2 finally
I quote him-
"
OK CHILL GUYS I HAVE THE SOLUTION FOR THE MEMORY REFERENCE PROBLEM. ITS VERY SIMPLE , I DIDNT THINK IT WILL WORK BUT I WAS AMAZED TO SEE IT DID. I ALMOST THREW MY HL CDS IN THE DUSTBIN...OK OK THE SOLUTION... CLICK PROPERTIES OF THE ICON U USE FOR RUNNING THE GAME. CLICK SHORTCUT TAB... IN THE TARGET ADD "-steam +mat_forcehardwaresync 0 +snd_async_prefetch_priority 1” WITHOUT QUOTES AT THE END INSTEAD OF JUST "-steam" "
Also, remove your windows temp files and have a clean installation.
It worked for me!
cya now, gotta meet Alyx :P
gans/