Photoshop problem

All right, I start up Photoshop (CS), and then goes over to "File/Open"...find my picture...and click "Open"...
...and nothing happens.
Same thing wiht "File/New"...and it even lets me pick the document size and everything...but as soon as I press "Ok", it just goes right back to the same blank screen that you get when you first start Photoshop...
...also, once in a while when a image does manage to open, I can't edit it in any way and I can't save it, unless as a jepg.
Thanks in advance,
Jeff
...and nothing happens.
Same thing wiht "File/New"...and it even lets me pick the document size and everything...but as soon as I press "Ok", it just goes right back to the same blank screen that you get when you first start Photoshop...
...also, once in a while when a image does manage to open, I can't edit it in any way and I can't save it, unless as a jepg.
Thanks in advance,
Jeff