Deleting those files is not even close to the same as doing a re-install.And you don't need to resort to a re-install.
Have to ask before anything else if you have already downloaded and installed the patches for all your EPs - if not, those need to be installed, preferably in the order in which you installed the EPs.
Patches here, just in case:
http://thesims2.ea.com/update/index.phpFirst, does this happen on only one particular lot or on any lot? If only one, then there is most probably a problem with that lot.
If all lots are so affected, there may be a hack or mod in any custom content you may have which is inhibiting the interaction.
Second, have you installed any custom robots or recolors of robots or of the robotics station or anything else in custom content related to robots or to the robotics station?
If so, remove those temporarily from your Downloads folder and then start the game up and go buy a new station and see if it functions as expected.
If the glitch still persists, try this:
Visit the lot where the 'bad' robotics station is.
Open the cheat box (Control-Shift-C).
Enter this cheat:
boolprop testingCheatsEnabled true
You might immediately get an error warning. If not, then shift-click on the robotics station and choose 'Force Error' and then 'Delete' from the error warning options.
Open the cheat box again and enter:
boolprop testingCheatsEnabled false
Then Quit the game. Then go into the Sims 2 folder and delete the groups.cache file there (if tehee is one). Re-start the game and purchase a fresh robotics station and see if the problem has been corrected.