2D Collision

So I need some help on collision with my player and the level itself. I’ve added gravity to the player so it would drop until it would hit the ground then stop dropping, but when the player goes down a hill, it goes down perfectly, but when I try to go back up it goes into the level and not back up the hill. Any help or tips?

OK, so I know I've only waited 1 day, so...is it good to use a .bmp made in paint as a level? or should I use data or something else? Although I dont really like the datas product or because it looks kind of "blocky" let alone know how to use it.

Use some kind of grid system, and use panels for pictures, rather than one big picture.That's the best way to do it.

Ooh ooh hey look at this thang I made :D!!!
http://blitzbasic.com/Community/posts.php?topic=77659

It's a 2D map editor that YOU can edit to make it your own.

When using 2d graphics, i've always found it better to move your character horizontal first, then check collisions, then move it vertical, then check collisions. That way, you reduce the chance of your character getting stuck or falling through. Also, when collisions are detected, always record the characters previous co-ords. If a collision is detected along the horizontal, then restore the characters previous x co-ord.

Only check once for bullets and such, AFTER you've done the characters movement both ways.