Hi cordoba, thanks for the reply.
It's ok for a while (10 mins or so) playing CD's etc. Then it goes crazy. Sometimes it goes into RDS search, sometimes wrong functions are happening randomly when any buttons are pressed.
Sometimes no buttons work at all and it is stuck playing a CD for about ten minutes, then it audibly fast forwards or rewinds the disk at random!
Then it won't let you do anything until the power is down for a while. After which, all is well again for a few minutes, but only a few minutes.
The other night I took the fuse out, re-entered the code after an hour or so, and it worked fine. But in the morning it went haywire again. It's been the same since.