Save As button greyed out in main menu(disabled)

I have inherited a ms access database that i am meant to alter and
make some changes to.

The database was original i believe created in Access 2000 while now i
am using Access 2002 and my OS is XP.

When i go to File and try to save i find the Save button and Save AS
buttons greyed out (disabled)!

It does or did at one stage keep asking me whether i wanted to convert
and i clicked yes or ok and it kept asking me this. eventually it went
away.

Would anyone know why my save is greyed out and why i kept getting
that convert popup even after clicking on ok.

If i create a new db then i have no probs?

Thanks