Problem with HP Officejet 8500

Hi Guys hopefully someone can help me here.

I have a G5 duel 1.8 powerPC which has an HP officejet 8500 installed via HP disk.

I am trying to print having just put in some new cartridges one of which is out of date but fully and I have done a print test and the print test show all four cartridges printing perfect but when i click print I get the following message:

The following cartridges are past their expiration dates: Magenta. You should remove or replace the expired cartridges or click OK to continue with the expired cartridges. HP cannot guarantee the quality or reliability of expired cartridges. Printer service or repairs required as a result of using expired cartridges will not be covered under warranty.

the problem I have is I cannot see the OK button I have tried the ok button on the printer that does nothing it specifically states click ok so i presume it should be on the screen. I have been to HP site to check for new software but they no longer support PowerPC 10.5.8 the drivers start at 10.6

Have you tried tapping the tab key and then tap return? That might do the same thing as tapping OK. I doubt you will be able to find an updated or newer driver for that printer.