wont move?

ok, i definitely have an interesting issue. For awhile I thought i burned the clutch up, because with the way this sounds, it doesn't seem like it could be anything else, but then it fixes itself and is fine. Well anyways when it gets hot out like today, I go to start my vehicle and drive it around and when I go to switch gears it wont accelerate. The Rmp's are getting higher, and I am pushing the gas and it just wont move any faster. This problem only seems to occur when it is hot outside though, because when it is cooler the truck runs fine. When I barely got home today because of this, my brother tried to figure out what the probelm was, and when he started the vehicle it wouldn't even move when he let out the clutch! He says I burned the clutch up. So when I went out just a little bit ago, I did get the vehicle to move when i let out the clutch, but i still could feel that it wasn't accelerating like it should when i push on the gas. I dunno what is wrong. If i burned up the clutch, why would it get better when the weather becomes cooler?

when it moved you probably had it on a piece of paper thin clutch disk and now it's all gone so it wont go no more unless you put new clutch,presure plate and throw out bearing..

but why would it run ok when it's cooler outside, and not want to move when it's warmer?