Can Someone please help me (crc) errors

So here is the problem.....
1.Alot of times when i download maps from fps banana i will get a CRC file is corrupt yet i can pass the link on to my other co-founder and its just fine for him???
2.I am also getting this same message in game while downloading new maps from other servers
( Cant CRC missing maps)
So if anyone can help me that would be great
I have tryed defraging my game files in steam and nothin.?.?.?.

CRC means cyclical redundancy check which means the archive containing the map file is corrupted and is most likely due to a problem with your archive program or internet connection. The fact that is happens both in game and out of game would seem to suggest that its your connection. Does your connection sometimes time out or get large lag spikes?

Large lag spikes yes ....i was running our clan server here at my house but i kept having lag issues so i took it over to my mates house and now it (the server) runs great.So thank you for your reply i guess i will give my isp a call and reem them lol TY so much.