Thanx a lot for your replies.
I'm facing another strange problem.
When i try to load ledtest.hex (LED blinking tutorial at http://www.iguanalabs.com/1stmicro.htm ) i get the following :

Filename : LEDTEST.HEX Used Memory : 81
Erasing(1/10) ...
Writing ...
Verify ...

Then a pop error comes : '$' is not a valid integer value.

The content of LEDTEST.HEX is

:020000000149B4
:0100030032CA
:01000B0032C2
:0100130032BA
:01001B0032B2
:0100230032AA
:1800250075880075890075D00075A800227F000FEFB4FFFB227E007DFC
:14003D00020E1132EE70FA1DED70F6221125B290113A014B63
:00000001FF

Please suggest something.

Strange enough i can successfully write and read any other hex files i tried.
But LEDTEST.HEX always gives the same error.

Regards

bips