Cannot Detach a model from a managed model?!

This seems to happen whenever, at some point, somebody opened the file with a geopak enabled session and then saved it. They don't have to necessarily do anything, as it seems that just by having windows/options open through their normal setup is enough to trigger the locking. At any rate, you'll need somebody with geopak to open the file, and run an mdl (should be preloaded by default) to "purge" the drawing from any smartness (openroads or geopak). 

In the key-in, type/enter:

Mdl load Bentley.Civil.Model.Tools.3.1.dll

then 

CIVIL CLEAN

then save. Open with regular v8i and you should be able to detach anything.

My 2c is that it can have something to do with the project explorer settings.

This seems to happen whenever, at some point, somebody opened the file with a geopak enabled session and then saved it. They don't have to necessarily do anything, as it seems that just by having windows/options open through their normal setup is enough to trigger the locking. At any rate, you'll need somebody with geopak to open the file, and run an mdl (should be preloaded by default) to "purge" the drawing from any smartness (openroads or geopak). 

In the key-in, type/enter:

Mdl load Bentley.Civil.Model.Tools.3.1.dll

then 

CIVIL CLEAN

then save. Open with regular v8i and you should be able to detach anything.

My 2c is that it can have something to do with the project explorer settings.

Again it only works if you or others have access to the extra civil software.. go back and  look at my fix to make a temporary file and then replace your bad file, then publish the instructions from Jesus De Luna above on CIVIL clean files that need to be shared. to avoid the locking.. Mostly should be an education process to designers and modellers not to lock files that are shared by others.. very annoying  when you cant get the culprit to fix it and you don't have the software to do it yourself.. we can't always wait for them...