I have neither Money 99 or Vista, but I do have a lot of older programs myself, so your post piqued my interest.  Found someone else with your problem:

 

http://forums.vnunet.com/message.jspa?messageID=947387

 

As for fixing it, or if it's fixable, I'm sorry I can't offer any advice - just thought you'd appreciate knowing you weren't alone.

let's try to check out the contentions of the (very interesting) preceding article:

1) is your current problem on a Vista system?

2) if so, did the problem occur after doing a windows update?

 

if not, what operating system are you using?   and what other changes (new programs?), if any, did you make (add) recently?

 

do you still have access to one of your other/older [pre-vista] systems, to see if money 99 will still run on them?

 

also:  just a wild thought, to test out the question of whether or not money 99 was set to "expire" after a certain date:

try (temporarily) changing your system/clock date... push it back a month... even a year... and see if money will run.   if so, this would suggest a built-in expiration.   if it still errs with the date set back (a year), then it's something else (like a recent update) causing the incompatibility.

and if you try this expiration test, be sure to re-set your system date to the current date afterwards!