CS:Source major lag spikes

[PcMe]

I'm ****ed, this is like the only game I play and I'm starting to get really bad lag spikes, where I won't move for a few seconds and I usually end up dead. I don't know what it is; I have the settings on what they're recommended to be on for my system, and even when I lowered them, I continued to get these lag spikes. My ping is usually below 100, so I doubt it's that either.
It happens on multiple servers, not just one - so I don't think it's the server I'm playing on. Is there any simple reason this is happening?
Thank you

 

[Ridlyn]

Im having this exaxt problem, i'll be playing on a server getting 40-60 Ping then all of sudden i spike up to 300-600 for no apparent reason, i closed all backround programs checked for viruses/spyware/adware none of the on my comp. This also happens in other games too. not just CS:S

CoD 2
CoD

 

[Ridlyn]

Help pls.

 

[Powerslave]

Pcme I have the same exact set up as you and I have no problems at all. Try re-installing css.