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HFSS failed to start with ot1000as.dll module fault

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Newbie level 1
Oct 26, 2010
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Hey guys, I need help on this. My HFSS has just failed to start. I'm using HFSS v11 on Windows 7 Ultimate, with compatibility mode to Win XP SP3. It crashes with these details:

Problem Event Name:	         APPCRASH
  Application Name:	        hfss.exe
  Application Version:
  Application Timestamp:	469da40d
  Fault Module Name:	         ot1000as.dll
  Fault Module Version:
  Fault Module Timestamp:	45bfa2fb
  Exception Code:                	c0000005
  Exception Offset:	         00083fca
  OS Version:	                6.1.7600.
  Locale ID:	1057
  Additional Information 1:	0a9e
  Additional Information 2:	0a9e372d3b4ad19135b953a78882e789
  Additional Information 3:	0a9e
  Additional Information 4:	0a9e372d3b4ad19135b953a78882e789

I suspect it was caused by an unclean shutdown (there was a blackout at my area) but I'm not sure.

I did a search and found no solution. Did an uninstall-reinstall but problem persists. One thread suggests deleting user config files but since I just reinstalled it, the folder is already empty (It is the Library/Documents/Ansoft/temp, or am I wrong?). I've also replaced ot1000as.dll with file from another HFSS user but no result. Before the crash, I can used the program just fine.

Has anybody encountered this problem too, and how you solved it?
Thank you.

ps: it was an evaluation version
Last edited:

Providing your evaluation period has not expired, I believe there is a corrupt
licence check file. These files are usually burried somwhere outside of Ansoft folder
and could be tricky to find.

I will give you the advice you would not like to hear:
Reformat your hard drive and install it all again.
I had sort of similar problem years ago, even Ansoft support team could not help.
So I killed the disc, re- installed the windows and the rest and it was OK.

Hope this helps.

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