Comminication fails suddenly

Development Tools IDE 1.x
1

After working with the IDE and my NANO 3.0 i suddenly get the error:

Binary sketch size: 8312 bytes (of a 30720 byte maximum)
C:\arduino\hardware/tools/avr/bin/avrdude -CC:\arduino\hardware/tools/avr/etc/avrdude.conf -v -v -v -v -patmega328p -cstk500v1 -P\.\COM24 -b57600 -D -Uflash:w:C:\Users\HFA73~1.ARE\AppData\Local\Temp\build1326008185081450831.tmp\NmraDccV01.cpp.hex:i

avrdude: Version 5.4-arduino, compiled on Oct 11 2007 at 19:12:32
Copyright (c) 2000-2005 Brian Dean, http://www.bdmicro.com/

System wide configuration file is "C:\arduino\hardware/tools/avr/etc/avrdude.conf"

Using Port : \.\COM24
Using Programmer : stk500v1
Overriding Baud Rate : 57600
avrdude: ser_open(): setting dtr
avrdude: Send: 0 [30] [20]
avrdude: Send: 0 [30] [20]
avrdude: Send: 0 [30] [20]
avrdude: Recv:
avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: Send: Q [51] [20]
avrdude: Recv:
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51

avrdude done. Thank you.

Resetting the computer, resetting the NANO did not solve the problem.
The used comport is present, when i send a character to the NANO the rx led flashes.
Anyone any idee?