Gmod always creates a crashdumb file for auto-send this error to somewhere ((I really dont know,i heard of this before))
You can find that file on ''Steam\SteamApps\common\GarrysMod'' It should be named like ''hl2_140713_crash_((Year))_((Month))_((Random Code))_((Random Code))_((Random Code))
Like '' hl2_140713_crash_2014_12_13T17_5_32C0 ''
If you can remove that old crash files and try to join again ((That wont help of course))
You will receive one of that files for your crash problem.
If you can upload it for us,i can help or Developers can help or someone can help. It can be about your Gmod,maybe not about your ram or somethin'.
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If you are running out of memory:
1. Go to start [[You can skip this step if you have Windows 8]]
2.Search for ''CMD''
3.Run it as Administrator
4.Type this command in cmd ''bcdedit /set IncreaseUserVa 8182
5. Reboot your computer.
Note: This action cant cause any problem for your computer [[Atleast,people saying nothing about it because i made a research before typing it here]] BUT if you dont trust,do not do that,i wont take any responsibility for any problems.
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This is all what i can say about your problem..I hope you get it fixed and join server as soon as possible.
Good Luck!