Search not working

Hello,
I've bought a new computer 2 days ago. It is a HP G62 B85SS. It works with W7 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

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...

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.