is my kx not working

help need my kx that i have when i take a shoot on av its very dark so i turn it of and on back to av then take more 3 or more then it is ok has any one had this to them and if so how to fix it ??it only dos this when i first turn it on for the first few shoots then clears up dont no y ????

That does sound like a fault to me, I think your best bet is to take it back to the dealer (or contact Pentax directly) and ask their advice.

Does it actually take pictures that are very dark, or do you mean very dark when you see them on the rear screen?
Have you got any examples of a dark picture and then an ok picture of the same scene?

If you've got examples, can you look at the EXIF details of those pictures, and preferably compare them to similar pictures that seem ok. To view the EXIF data you can use something like PhotoMe on Windows - the interesting stuff is the exposure information. What I'm trying to determine is whether the first shots are completely underexposed or there is something else going on like a large EV compensation set.

and when u see them on the rear screen ??