Try a different Usb port.
Hp says you have five......try them all.
Keep in mind.
On your machine your writing "to" the unit.
On another machine your reading "from" the unit.
Maybe flip that around and test.
When transferring large files to my Diesel 16GB flash drive, the fastest speed I get is 4.3MB/s per TeraCopy. When I copy the file back to another PC, actually an older PC than mine I get speeds in excess of 11 MB/s.
My desktop PC is a HP Pavilion Elite E9160F with Windows 7 Home Premium 64 bit installed.
Any ideas on why the slow speeds ? Cant be the drive because it has fast speeds when I transfer the file to another PC.