I am just learning Fireworks MX 2004 and in the last 2 days of trying to create sites keep getting
a message when I try to preview the pages it reads

00000001_gif already exists. Continue and replace existing files.
OK Cancel

If I click cancel the page is jumbled up. Ok will work if evry slice is given a unique name
I have tried deleting all temp files. If I dont do this then the page is all jumbled when I preview it.
If I name every individual slice it will sometimes work.
This has just started to happen. I am trying teach fireworks to students, after a few years of ImageReady and Golive and I need to know how to fix this if it starts happening to the kids.
Cheers