AutoCAD for Mac

[#1]

I have a 21.5", 2011 iMac running on Mac OS X Lion 10.7.3. I have the AMD Radeon HD 6750M graphics card and a 2.5 GHz Intel Core i5 processor.

I downloaded AutoCAD for Students, and it worked well for several days, but then began to crash whenever I would change layers.  After successfully restarting AutoCAD after those crashes, it now crashes before fully opening and has not been able to open for several weeks.

I get the error message: Unhandled Exception (Version E.49.H.554(x64)).  I have looked through other threads for a solution; this version of AutoCAD apparently doesn't support the AutoCAD 2011 for Mac updates though?

Help?

[#2]

You have to install all 3 Updates for AC 2011 for Mac in order to be able to run it on Lion.

Maxim

[#3]

I have tried to install all three updates, but have never succeeded.  Each time I try, I get the message "You do not have a copy of AutoCAD installed which can be updated."  

[#4]

Can you try to create new account with admin privileges on you Mac and install Update from this new account?

Maxim

[#5]

I tried this... It doesn't work