Version: 0.50.80 (using KDE 4.1.0)
Installed from: Ubuntu Packages
When I put $$ $$ in a conversation with the KopeTeX plugin activated, a huge white picture is generated.
Notice that there's a space between $$ and $$.
Confirmed with KDE 3.5.9, and KDE 4.1.x r856359.
Fixed for KDE 4.2 (r857034) and KDE 4.1.2 (r857035).