I think the issue here is that you're doing it all wrong. Its not a plugin issue.
Link me your sv_downloadurl. Id bet the issue is there.
I used http myurl, insta fail, then www, fail again, then I changed the folder settings in my fast dload and instantly people stopped crashing.
http://checkster.com/csgo/
did not work
so I did
checkster.com/csgo/
remove the /
The last one naturally, and its due to diff OS, some win nix etc, they read the / diff, so just remove that part and you should be fine