Panasonic DMR-E100H troubles finalizing DVD-R (cheap discs)

[MainMarcel]

Hi,

Jealously I watch the prices fall on DVD+R while prices DVD-R are still sometimes double them. Most DVD-R prices on 'tier-1' brands (Panasonic, TDK, Maxell) range from about 2 to 3 euros in non-internet shops. I have tried some cheaper brands as well (Imation, MMore, ThatsWrite, Hi-Space) but they are not fully compliant with my Panasonic DMR-E100H.

Some cheaper DVD-Rs either:

1. won't finalize (which is very frustrating if you already erased the film from HDD.)
   won't record in High Speed mode even while the package guarantees it.
   are simply not recognized (sometimes an Imation 10-pack is recognized for only 50%.)

Anybody had any similair experiences?
Tips?
Is there a software (firmware) upgrade?

Thanks in advance!
Marcel