Garry's Mod folder keeps switching to Read-Only.

Basically, whenever I join a server I have the default Half-Life 2 HUD, the scoreboard doesn’t work, and I can’t move. So far, I’ve tried wiping my cache and lua folders, and completely reinstalling GMod, and of course, turning off read-only on the Garry’s Mod folder (at which point it switches itself back to read-only.)

I’d really like some help please.