I have the latest Linux HLDS with CS 1.3 on a Mandrake 8.0 P3 733/384MB. This is for context.
When I stop HLDS Server it didn't freed the RAM. I m not a beast at Linux so I don't know if it's a Microsoft compliant bug or a Valve bug or a Linux bug or a linux administrator bug ! :o) (Hey ! don't kick my ass like that !!).

