1. Close the game
2. Verify game files integrity: Go to your profile --> Library --> Right click on hl2dm and select properties --> Verify game files integrity
3. GO TO: C:\Program Files (x86)\Steam\steamapps\common\Half-Life 2 Deathmatch
4. do a search for *.cache (this means all files that contain the word cache in them
5. Select all and delete
Fixed
