Selection malfunction in 2005 Mechanical

[Anonymous]

Every now and then, I have this re-occuring problem in 2005 Mechanical. I have not seen this in plain 2005, nor in Mechanical Desktop 2005. I select a line or circle on the screen and it highlights, but I cannot delete it by hitting the "delete" key on the keyboard nor by right clicking and selecting erase. I am able to move it only by selecting a grip point and dragging it to a new area. Also I've noticed at these times that I can only save by hitting "ctrl s" on the keyboard...it seems that the icon for "save" is not recognized. I have to close the drawing and restart AutoCAD, then I am allowed to delete the features I don't want. This has happened on several occasions since loading 2005. Any thoughts out there? Thanks, Bill