Fog problem, has to do with LUA errors looping?

was playing on a Sandbox server in flatgrass, the first few hours were fine, but all sudden, two people came in and made the server lag like it was a snail on acid. the screen if you look up, its like a glossy glass like scenery when you go near them, but it goes away when you enter a vehicle or look down on the ground. closed Gmod and wake up only to find my computer crashed. could be my video card or processor, but most likely the latter.
Is it some sort of exploit or a glitch?

here are my specs to verify.

Operating System: Windows XP Professional (5.1, Build 2600) Service Pack 3 (2600.xpsp_sp3_gdr.101209-1647)
Language: English (Regional Setting: English)
System Manufacturer: Dell Inc.
System Model: Inspiron 530
BIOS: Phoenix - AwardBIOS v6.00PG
Processor: Intel® Celeron® CPU 440 @ 2.00GHz
Memory: 3326MB RAM
Page File: 872MB used, 4337MB available
Windows Dir: C:\WINDOWS
DirectX Version: DirectX 9.0c (4.09.0000.0904)
DX Setup Parameters: Not found
DxDiag Version: 5.03.2600.5512 32bit Unicode

Celeron processors are bad bad bad!

you need a better processor. could be your graphics card aswell, not too sure though because you didn’t list it