Hi,

I successfully installed AutoCAD Mechanical 2011 a month ago and just
recently, I had the chance to look at it in more depth. Unfortunately,
not realising that I hadn't installed Inventor for all the 3D assembly
stuff I needed, I tried to uninstall Mechanical - which failed towards
the end for some unknown error. I then deleted all of it's files from my
C:\ and upon finding about about inventor, tried reinstalling from the
installation files I still had. However, the setup states that AutoCAD
Mechanical 2011 is still installed and thus won't let me reinstall it.
Exasperated, I've installed Mechanical 2010 but would like my 2011
version back. How can I fix this?

Thank you!

You don't say how you deleted all the files from your C:\ drive but AutoDesk does have a procedure for uninstalling an application prior to a clean install posted on its website.  You may have to give it a read and see what you may have missed.

Didn't work, I've gone through the steps - by how I deleted i mean, I literally, manually deleted the files (after the 1st uninstall failed) into the recycle bin and got rid of them. So a standard uninstall via Control panel - add/remove programs became impossible. After doing all the remnant clean ups, I still can't reinstall acad mech 2011, as it keeps saying that there is a newer version installed already even though there are no more autocad products on my computer!! HELP!!!

So are you saying that you went here http://usa.autodesk.com/adsk/servlet/ps/dl/item?siteID=123112&id=2887771&linkID=9240617, followed the instructions and removed all files from all directories and from the registry and you still can't reinstall?

Yup! been drivin me nuts,finally, i found a reg cleaner via which i deleted further remnants of auto mech 2011 and tried reinstalling. momentarily the problem was solved in that the options weren't greyed out anymore. but installing it now has another problem - it's having trouble getting access to a key in the reg due to some permission error or something. followed the steps on autocad's help website and the problem continues to reappear. am going to try disabling the antivirus (possible cause) and see what happens. what do you think?

I've heard that AV programs can disrupt installation, so turning yours off may help.You didn't mention what operating system you're on? If you're on Vista or Windows 7 you may need to adjust your security settings.

well, disabling antivirus didn't do it. btw, i'm running win 7,i found a similar complaint online and that person used a windows registry cleaner to find the remaining keys and subkeys still attached to mech 2011, it was actually released by microsoft to solve a problem with office installation. but windows then took it off their website saying it caused instability. but i used it anyway - and it worked until I tried reinstalling and then it couldn't get access into the registry for installing (new problem!), so i just gave up, restored from an earlier system image, redownloaded from autocad and reinstalled everything. and now, it's all good. moral of the story: don't delete files until the computer has said ok to delete!!thanks for all the help though :)