Garry's Mod Chat Problem

Howdy. Of course, you may assume that my Gmod is acting up again.

I’ll just get to the point.
When Gmod is used for about a half an hour, my chat acts up. Whenever I use the A key, my entire chat is reset. When Z is used, it takes place of the previous letter. When V is pressed, any text copied into clipboard is pasted there. Also, the backspace won’t do anything.
I must reboot Gmod every time this happens, otherwise it won’t get better. I’ve reinstalled many times, but still no success. It happens on EVERY server I go in, INCLUDING SINGLEPLAYER!
Please help, it’s getting really aggravating!

As for system specs:

System Information

Operating System: Windows 7 Ultimate 32-bit (6.1, Build 7600) (7600.win7_gdr.091207-1941)
Language: English (Regional Setting: English)
System Manufacturer: TOSHIBA
System Model: Satellite L505D
BIOS: InsydeH2O Version 1.20
Processor: AMD Athlon™ X2 Dual-Core QL-65 (2 CPUs), ~2.1GHz
Memory: 3072MB RAM
Available OS Memory: 2814MB RAM

I’ve never had this problem before until about a month ago.

Sounds like your shift key is stuck or something (ctrl-a = select all, no idea bout z, and ctrl-v = paste).

It’s fine outside of Garry’s Mod.