How do you know it has the latest firmware? When sold to you it more than likely had the 113 firmware still. I think anyway! Most burning programs will display the firmware version or you can get a little program called 'CHKRW.EXE'!
Ive just reread your original post and nowhere does it say you are using the 118 firmware! I think this is the latest! But like i said from what I have read some people are having problems with it! I use 'Nils' (he's the guy who made the firmware hack) 116 firmware. It allows you to use 4x at 8x therefore saving money on the cost of disks. It also does other things which I cant excactly remember.
Look if worse comes to worse I am willing to email the programs and files you will need! There is a readme that comes with it all to explain what to do and also explains what it does! Just PM your email address to me. I only have a 56k dialup but the files when zipped are only 1,166kb's all up! I will only email NIls 116 firmware hack as this is what I'm using, will also email CHKRW (To check the firmware) and DVRFlash.exe (to perform the Upgrade), plus the readme! Let me know.
Or if you prefer to do the searching yourself go here:
http://pioneerdvd.rpc1.org/