Programmer is not responding (correctly)

Ok. I changed the upload.verbose-line.

The first couple of times, the output was

Binary sketch size: 3674 bytes (of a 7168 byte maximum)
uisp -v=4 -dpart=atmega8 -dprog=stk500 -dserial=/dev/ttyUSB0 -dspeed=19200 --upload if=/home/alfonsvh/Desktop/arduino-0007/examples/led_blink/applet/led_blink.hex

Transmit: { 0 [30] [20] }
Receive: { . [00] }
Receive: { . [00] }
[VP 1] Device is not responding correctly.

I kept on trying, and once I got this output:

Binary sketch size: 3674 bytes (of a 7168 byte maximum)
uisp -v=4 -dpart=atmega8 -dprog=stk500 -dserial=/dev/ttyUSB0 -dspeed=19200 --upload if=/home/alfonsvh/Desktop/arduino-0007/examples/led_blink/applet/led_blink.hex

Transmit: { 0 [30] [20] }
Receive: { . [14] . [10] }
Transmit: { B [42] p [70] . [00] . [00] . [01] . [01] . [01] . [01] . [02] . [ff] . [ff] . [ff] . [ff] . [00] @ [40] . [02] . [00] . [00] . [00] [20] . [00] [20] }
Receive: { . [14] . [10] }
Transmit: { A [41] . [82] [20] }
Receive: { . [8a] }
Receive: { . [89] . [10] }
Transmit: { A [41] . [81] [20] }
Receive: { . [14] . [01] . [10] }
Transmit: { E [45] . [04] . [04] . [d7] . [a0] . [01] [20] }
Receive: { . [14] . [10] }
Transmit: { P [50] [20] }
Receive: { . [14] . [10] }
Transmit: { u [75] [20] }
Receive: { . [14] . [1e] . [93] . [07] . [10] }
Transmit: { Q [51] [20] }
Receive: { . [14] . [10] }
Vendor Code: 0x1e
Part Family: 0x93
Part Number: 0x07
Atmel AVR ATmega8 is found.
Page Write Enabled, size=64
FLASH Write Delay (t_wd_flash): 12500 us
EEPROM Write Delay (t_wd_eeprom): 25000 us
Transmit: { 0 [30] [20] }
Receive: { . [00] . [fb] }
Firmware Version: 1.137
[VP 1] Device is not responding correctly.

I only saw this type of output once; each time I try to upload again, I get:

Binary sketch size: 3674 bytes (of a 7168 byte maximum)
uisp -v=4 -dpart=atmega8 -dprog=stk500 -dserial=/dev/ttyUSB0 -dspeed=19200 --upload if=/home/alfonsvh/Desktop/arduino-0007/examples/led_blink/applet/led_blink.hex

Transmit: { 0 [30] [20] }
Programmer is not responding.

Any ideas?