Memory Card error

My Pentax istdl is showing Memory card error message , i was using 1Gb memory for a long time & now this message appers & i replaced with another new card still the message is same , when i used old 256MB card it is working , i tried many new SD cards & it is showing Memory card error. i updated firmware still same , pls help me to resolve my issue.

Well, you can try resetting the camera to manufacturers defaults and remove all the batteries for a minute. Sometimes strange issues "can" be fixed this way.

Unfortunately last year, my K10D did the same sort of thing.
I finally had it sent in for repair and Pentax essentially replaced the entire insides. (motherboard, sensor, a few other things).