30D - file numbering

this just started happening recently....not really sure what is causing it.

when i transfer the pictures to my computer and erase all the photos from the CF card, the file number would start again at IMG_0001 when i put it back in the 30D. i've been trying to get it to continue from the previous image number. Any ideas why the file number is not continuing as it should be? For example, if my last image was IMG_0099, and i deleted all the pics from the CF card, shouldn't the next image file number be IMG_0100 when i put the empty CF card back into the camera and start shooting? Instead, it is starting back over that IMG_0001 again.

i have file numbering set to continous, and am using a sandisk extreme III CF card. The folder number on the CF card is at 250.

I do the same thing with my camera and it keeps the last file number on the body as well as the picture number. Mine is also set to continuous. Not sure whats going on with yours? Mine starts with a _97Y not an IMG_

Take Care,
Cheers, Patrick