Hi - sorry for the delay :o.
Firmware is the instructions for the recorder to work. It's software stored in memory within your DVDR. Sometimes a manufacturer like Philips will issue updates to fix problems or maybe allow your recorder to use faster discs, and you have to replace the old firmware instructions with the new ones.
For Philips this is done by downloading the new firmware and burning it to a CD. The new one for your machine is about 48 MB so you'd probably need a broadband connection as well as a CD writer.
The problems you describe with your recorder might be fixed by a firmware upgrade, but maybe not. Let me know whether you would like to try...