Help i have this wierd lag

Okay so i was playing TTT and my computer was lagging and everytime i would attempt at switching weapons it would take a minute for my person to change the weapon after i clicked it. And my chat is delayed as well i would type my message and a minute later it would finally show up while the game was running smoothly.

Anyone heard of this before cause i cant figure out what it is I’ve searched on the internet but i didnt find any body experiencing lag with these symptoms.

And its a pain in the ass cause i cant talk at all so when someone asks me was i the traitor i would type in my messege, they would kill me cause i couldnt respond in time and while im a spectator my message would finally be displayed. And people are like whhaat?

Uh, I know I ask this a lot, but system specs?

Processor: AMD Athlon™ 64 Processor 3200+ 2.01 GHz
RAM: 4.00GB (2.00 GB usable)
Graphics Card: Geforce 9800 GT
my lowest subscore is a 3.9 which is my processor my highest is my graphics card which is a 6.8

A tip is to turn on “net_graph 1” in the console, and monitor your ping and see if it randomly goes up, if it does, that is your problem. I had a very unstable connection before where my ping randomly went up to 600 on a server that I usually have ~30 ping on. If this is your problem, there are various solutions for you. Tell me if this is the problem.