I'm no Ubuntu expert but I have had brief experience with Linux in the past and use it a bit at my university.
Today I had an issue with the Dash search function.
Specifically I downloaded a program called Teamspeak 3 to my /Downloads folder. I then executed the .run file and installed the program, which resulted in a folder appearing in my /Downloads folder containing the program and associated files.
I ran the program a few times from that location but thought there must be a better place to store the files. I used the sudo mv command to the move the folder into /opt. I later realised the program had been running while I did this but it didn't kick up any errors. This was no problem, but when I searched the term 'Teamspeak' in the Dash it would still show the /Downloads folder instead of the /opt folder.
So the problem is simply that the Dash search hasn't updated the folder's location. The program runs fine from /opt so thats not an issue.
Any assistance would be much appreciated :)