I worked on the property management side for awhile and this is something you definitely should be questioning!
Do you still have your original lease documents that you signed in 1993? Generally speaking when you go month-to-month, unless you sign a new legally binding lease document, the same lease is instilled minus the month-to-month rental amount.
Also, in terms of a notice to vacate, each lease can differ. I worked at a community where we required a 30 notice to vacate, though we were transitioning into a 60 day notice to vacate. I do know in Colorado, a management company can take 60 days to return a deposit.
Hope this helps, but at the end of the day, there are many great legal avenues for you to check into if you are still feeling at a loss and not getting your matter dealt with.
Madison & Company
(303) 847 -2312