Adobe's advice for those that have upgraded to Mac OS X Leopard is that for Photoshop Elements 4 and earlier the user is 'likely to encounter issues for which there is no resolution.'
I have yet to encounter any adverse effects from using PE4 with Leopard. Any Mac user had problems with this version of Elements?

Tony, are you on a PPC or an intel machine? My observation is that PPC users have few problems with older programs when moving up to Leopard. It seems to be the folks trying to use older software under Leopard on an intel Mac. Sometimes, in the later case, doing a "get info" on a program and checking the box to run under Rosetta will solve the problem. Other times not.

Your observation may well be right. I'm using a 5 year old G4 PPC desktop.
Tony

I am using a 1 1/2 year old intel and had no trouble with 4 except it was slow as a slug and would occasionally shut down for no apparent reason. Now have the Photoshop E6 and it is fast, really a fantastic difference, and certainly head and shoulders above the 4.
john sr