that my Hard Drive would expand by itself.
You probably mean shrinking. You seem to have a phobia about your HD size but I don't think you have much to worry about.
So, someone is downloading widgets onto your machine without your knowledge and you are not downloading updates.
You should be doing the latter and confessing to doing the former. Widgets, while small, use a LOT of memory, especially virtual memory, and this eats HD space.
Is this the same 40Gb drive you have posted about twice before? This drive, while sold as 40Gb, does not format out at 40Gb. This is because of the way that bytes are counted. As soon as that drive was initialized, it lost around 1.5 Gb, if not more.
By the way, what was the gas widget?
For the last couple of weeks my mac's HD has been expanding, leaving me with less and less free space. I haven't downloaded any programs or updates, and I dont think that a few widgets here and there should account for nearly 2GB of space. I have OnyX and use it almost every night to clean the HD but it doesn't seem to do anything. What's going on?
Also, what happened to the gas widget?