Didn't read your post carefully, I thought you wanted to enable it...
Anyway, try typing "net_graph 0" and "cl_showfps 0" in your console and see if it disappears.
Interesting coincidence, I've got the exact same problem on my HP laptop (I get a "memory could not be read" error occasionally too).
I've got an Intel 945 integrated GPU.
I started looking around here this morning to see if there were other people with the same problem, and I found a simple fix...
This is just from my memory, so I'm not sure if these are the exact commands, but I'm almost certain that they are.
net_graph (possible options are 0, 1, 2 and 3) to get a graph in one of the corners (which displays how much information is being sent and received, but also displays your current...
I will most likely place an order tomorrow or sometime in the beginning of next week.
I'm getting an Athlon 4200+ (either that or a 4400+ depending on if I can find out if they've got it in their stock or not) and a MSI K8T800 mobo, it'll definately be a step up from my current 1,7ghz Celeron...
Actually, I moved it from the Half-Life 2 forum, but anyway, back on topic;
as Harryz said, try reinstalling/redownloading, I can't really see any other possible solution.