Unable to install Current Snapshot ISO via USB attached CD drive

Hello
 I am using both a Tyan S2881 and S2882 motherboard with Opteron Processor.

 I have been trying to install the 7.X amd64 snapshot for some time now via A USB attached CD rom,
(same as I always have for 4, 5 and 6) But when using a 7 snapshot disk, the install always borks
at the same place. 

 I can install the snapshots just fine if I ATA attach to the cd unit, but I cannot if the
 CD unit is connected via USB. 

The errors are always:

F1 screen
 Write failure transfer! (wrote -1 bytes of 1425408 bytes)

F2 screen
....
 /stand/gunzip : <fd:0>: too many length or distance symbols
 /stand/cpio: premature end of file

F1 Retry:
 Write Failure On Transfer 
 Wrote -1 bytes of 1425408 bytes
 /stand/gunzip <fd:0>: invalid code length set


 Being able to install via USB is very important to me. It seems a shame 7 would be broken in this
way.

 Might anyone know what could be happening? I can swap the disk with a 6.X disk and it ill install
via USB just fine. I also cannot install To a USB attached drive using 7, but I can with 6.

 I have tried with the last 3 snapshots up to 200709.

 Thanks!

  Nicole

The Large Print Giveth And The Small Print Taketh Away
 -- Anon