Quartus II v8.1 Error, please help me

Hi all,

I have an error when i try to start quartus II version 8.1:

Internal Error: Sub-system: ATCL, File: /quartus/ccl/atcl/atcl_root.cpp, Line: 1792

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Error found while sourcing: c:/altera/81/quartus/common/tcl/internal/init/project.pkg_info

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invalid command name "INDX(

Stack Trace:

0x42184 : (kloehk)

End-trace

Quartus II Version 8.1 Build 163 10/28/2008 SJ Full Version

Could you tell me how to fix this error?

Any answers are welcome. I am looking forward to see your respond as soon as possible.

Tri