"Image is not stored" (Huh...?)

[lilyin00]

I have a Pentax ISD and I'm using a Sandisk II card with it. After a number of pictures, I would take a picture and then the screen would say "Image is not stored" and it wasn't saved in the card.
But then I would take another picture and the picture would be saved.
I'm not sure if it did that because I was out of memory (but the small screen on top that shows the battery and such had a number of about 350, but I'm not exactly sure what that numbers is referring to, either) or something like that.
So I was just wondering if anyone could explain to me why it would randomly say "image is not stored" and what the number on the top screen near the on/off switch means.
Thanks.

 

[Garbz]

Storage problems could indicate the memory card is on the way out. Is it a new card or a relatively old one? They don't have an infinite life.

 

[lilyin00]

The media card is new- the first time I had used it (ever).
It hasn't happened again, but I did just upload all of my pictures and delete everything on the card.
So now I'm just trying to figure out what the numbers on the top screen thing mean.