Outlook Index search not Work

I am trying to do a search inside of Outlook 2010.  When I go to type in my search field, a box pops up and says that

SEARCH RESULTS MAY BE INCOMPLETE BECAUSE ITEMS ARE STILL BEING INDEXED. CLICK HERE FOR MORE DETAILS.

So I click on that and a box pops up that says:

OUTLOOK IS CURRENTLY INDEXING YOUR ITEMS AND 39122 ITEMS REMAINING TO BE INDEXED.

 So then I go to OPTIONS and I look under the tab called SEARCH.... and then I go to INDEXING OPTIONS... it says

40 ITEMS INDEXED.   INSUFFICIENT DISK SPACE TO CONTINUE INDEXING. SEARCH RESULTS MIGHT NOT BE COMPLETE.