I have a Wacom Graphire3 tablet which I have used with various Macs for many years. It has stopped working! I have anIntel PowerBook running 10.7.5
First I had a message at startup that the 'Tablet software hadn't beed loaded because it didn't have the correct security', I have now downloaded a new driver 3.5.2-2 but it still doesn't work. When I try to configure it in preferences it says that: 'a supported tablet was not found on the system'
The small light comes on when the usb is connected but that's it.
Any suggestions?

I'll start with the two three obvious questions:

1. Have you tried the tablet in more than one USB port?

2. Have you tried it with another Mac?

Edit: 3. Have you tried it with a different USB cable?

Good luck.

And check that the usb cable, at the tablet end, is in the correct orientation. I have a USB microphone (a Blue Snowball), that will light up as if it's connected, but won't work. I found that the cable can be inserted upside down (don't get me started on the stupidness of the "square" end of usb cables...).

Because the USB connector involved is vertically asymmetrical due to a plastic core, this is only possible when either the connector or the port (or both) is damaged. If the Mac's port is damaged, a known-good cable may still not work, depending on its orientation in that faulty port.

While I would normally have agreed with you, it isn't true on the microphone I mention.

It appears I should have said 'damaged or not made to standards'.
Of course, that doesn't detract any from the annoyance this may cause.

Thanks for the ideas. The tablet doesn't work in either of my USB ports, but they work ok with other devices. I have tried it with another Mac, it works fine. The USB lead is integral to the tablet so I can't change it (but it obviously works!).
The other Mac is a MacBook running 10.6.8