Hi Dave...
I'd suggest stepping out of the sketcher and back to the model tree. Select the feature and try to delete it. You don't have to actually delete it... just wait until the system highlights the other features dependent upon the sketch. Chances are one of those other features is preventing the deletion.
For example, we all know if you try to delete a sketcher entity that's a reference for another piece of geometry, an error will pop up. We also know that you cannot remove a sketched entity that's related to a pattern or mirror. But there are some other occasions where you cannot remove a sketched entity that don't throw an error message. The first place to start is always by seeing what other features are using the problem entity as a reference. Maybe it's a form feature for a sheet metal part. Maybe it's a piece of geometry used in a copy/paste special... or a group.
I can't diagnose the problem without actually seeing the part... but if I were investigating, the first thing I would do is look for references. You can also try the reference viewer for this (duh, that might be easier!). If I were investigating, I'd SAVE A COPY of the part... then I'd start deleting items that reference the sketch. Work from the bottom up (delete the last reference first). Keep trying to remove the entity until it works. Once you can remove the entity, you've found the correct reference.
I'd make a note of which feature was causing the sketch to 'lock up' like this and warn the rest of your people about the problem. I'd also report it back here so the rest of us can benefit.
Thanks!
-Brian
Brian K. Martin
Sr. Mechanical/Application Engineer
SGT, Inc. under contract to
NASA Goddard Space Flight Center
301.286.0059 (NASA Office)
443.421.2532 (Cell)
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