Thanks ckaa,
I might see if I can get an older version of the drivers and see what happens if I try to install them.
Unfortunately I dont have a USB Blaster, so my driver issues are slightly different.
I tried installing the Win2000 ones as legacy but Windows claimed it couldn't find any suitable ones. I assumed that this and the refusal to load the installed driver indicated a security problem and was looking up how to circumvent it when I found that Altera don't support 64bit systems with their ByteBlaster driver.
I tried to run it in XP Mode (I have a 32 bit VM in this) but still nothing.
In the meantime I found an old laptop with no display that I am using to try and connect to my CPLD but my JTAG cable is refusing to work; I am getting quite fed up of this CPLD and am wishing i'd just bought a Terasic USB blaster to begin with.