possible heater issue?

[biggie03]

2000 ls8 sport
When I have the heat on, it works fine as long I'm driving. However, after I've been running the car for a while, when I stop I get a strong smell of something burning, but as soon as I begin driving again the smell goes away. I have been told its possible that my cats are clogged (which I have been told by the automotive shop that they are) and thats whats causing the smell. (the smell is similar to burning oil, not rotten eggs/sulfer) Has any one experienced this or knows what the problem could be?

 

[biggie03]

A follow up:
After reading through some posts I have noticed some similarities between my problem and some other peoples. One person noticed some smoke under the hood and the smell of burning rubber in the cabin (which is probably closer to the smell I have been getting) while the heater was on and someone replied that it may be the belt catching on a stuck pully. I did investigate the smell one day and did notice a small amount of smoke coming from around the area underneath the engine, so this possible cause is starting to fit my scenario. If this is a stuck pully, which one could it be, given that the smoke was coming from the lower section of the engine compartment?

 

[pagluy]

Do you perhaps have a low "hum" when the heater fan is on, that changes with how fast the air is blowing?

I have noticed the slight burning smell (sometimes) in the new car, and for the first few days the belt did squeal a little. I'm going to give it some time to see if it goes away before I bother the dealer again, but something seems screwey here.

 

[kwazy]

i have the same smell and it only happens when the heat is on and i have been driving for a bit. has anyone figured it out yet. thanks