Downloading ELF Process failed

[Altera_Forum]

previously my Nios was working, but it suddenly come out with such a error(downloading elf process failed) although i try it with a very simple nios system with just consist of on chip memory and nios2. 

 already reinstalled the quartus and eds twice. i try with difference system(sdram,flash) and change another DE1, but same error encountered.  what should i do to resolve this problem.   my system: windows xp quartus 10.1 web edition NIOS2 EDS 10.1 DE1  thank you in advance

[Altera_Forum]

Based on what I see in the error.bmp it is failing on download. 

SBT download the elf file, but on verification, it could not confirm that the correct data was downloaded into the onchipmem. Most likely this happens when your design does not meet timing.  Since you mentioned that it was working, then what I can think of is change of temperature, FPGA get heated up, device broken, and so on...  You might want to double check the board setting as well.  If you are using correct source of clock, power is given correctly, etc.

[Altera_Forum]

i have no idea what is going on of my design!!! 

i uninstalled the 10.1 version and installed with the latest 10.1 sp1, then re-configure the nios same as previous design, but it worked. anyway, thanks for you replied

[Altera_Forum]

--- Quote Start ---  i have no idea what is going on of my design!!! i uninstalled the 10.1 version and installed with the latest 10.1 sp1, then re-configure the nios same as previous design, but it worked. anyway, thanks for you replied  --- Quote End ---    Hi,   I'm having the same problem. So urs worked on 10.1 SP1? If so, is it the free or full version?