Burning High fuses fails

Hi, I tried it now several times to burn the High fuses on two of my m168 to "FF", yet they become every time 07 again. Besides this my m168 work flawlessly, yet this could be the reason for some trouble though... anyhow, the question is: is there something wrong about my AVRs or is it something esle since i dont believe that two of them are faulty..

Are you handling the lock bit correctly before and after trying to change fuses bits? From the datasheet:

“Note that the Fuse bits are locked if
Lock bit1 (LB1) is programmed. Program the Fuse bits before programming the Lock bits.”

Hm, didnt know about these… so if i understand that correctly i got to clear them in order to set the fuses?

Ok, set the lock bits to FF and still no result. THis is the output for the HIGH fuses:

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.14s

avrdude: Device signature = 0x1e9406
avrdude: reading input file "0xFF"
avrdude: writing efuse (1 bytes):

Writing |                                                    | 0% 0.00s ***faile
d;
Writing | ################################################## | 100% 0.32s

avrdude: 1 bytes of efuse written
avrdude: verifying efuse memory against 0xFF:
avrdude: load data efuse data from input file 0xFF:
avrdude: input file 0xFF contains 1 bytes
avrdude: reading on-chip efuse data:

Reading | ################################################## | 100% 0.02s

avrdude: verifying ...
avrdude: verification error, first mismatch at byte 0x0000
         0xff != 0x07
avrdude: verification error; content mismatch

avrdude: safemode: efuse changed! Was ff, and is now 7
Would you like this fuse to be changed back? [y/n]