Windows 7: Search not working

Hello,
I've bought a new computer 2 days ago. It is a HP G62 B85SS. It works with Windows 7 premium. The search option doesn't work with other units than c: eg. my external disk or a CD, or a USB key. It seems it doesnt' work neither with parts of C: because sometimes I found results for a given search, but not all the time, concerning files that actually are placed in c:. How can I configurate the search for working with the whole system? thanks in advance
Germà

Are you saying at times you do get the desired results?

No no, what I mean is that sometimes I found "some" results. Exemple if I look for a given MSword document from my documents in c: or other units, there is no results. But if I write the letter "s" alone in my search, it founds all the programs and panel control services containing the letter s in the title. As far as I can do only a new research when I found some results (with no results I can't see the "new search" option), I've done it from the "s" results so that I've expanded the search to the whole system, and only then I've found files from the other units. The problem is that obtaining a list with the thousands of files from my external disk containing "s" in the title, doesn't help too much...

Ummm I've found other threads concerning the same problem so I am looking for answers there. By now it seems that this can be solved by indexating all the units in the search settings so this is what I am trying now...

You can try this
How to Improve Search in Windows 7

With a warning:
Write down everything that is changed. In case it does not work out or you do not like it you can go back to default.
I have not tried these changes, I am happy with search. It works the way you describe, but I do not use it much

Start with a system restore point.

Hello again. I've done all the advices contained in this link, including the indexation of 50000 documents and I've restarted the computer. The result is not change at all: the search option works only for control panel and program files. What else can I do?

Otherwise what do you mean by start with a system restore point? do you mean only in case I'd provoked any undesired results with this operation isn't it? if so, there has been no problem because nothing has changed.

Yes, I think it is good policy to make a restore point before making changes. I have helped so many, that did not have a restore point. A small problem becomes a big one.

The Windows 7 search feature is really incredible if you know how to use it. First, I assume when you speak of "units" you are referring to a physical drive? Second, Windows 7 search will find files that are indexed on your C:\ drive. These files include all libraries, email, contacts, document content, programs, and system utilities. It will not search external, non-indexed drives without a little effort on your part. Suppose you're looking for a document named "can't find" on your external G:\ drive. When you type "can't find" in the search box and get 0 results, keep an eye on the bottom of the results window. Click on "see more results" This will open a window allowing you to search for your file outside of the index. Most of the time you'll select "computer". This will search your entire system, including external drives, flash drives, network drives, etc.
If you know the file is on drive D:\, open drive D:\ in an explorer window and enter the file name in the search box at the top.