But the PC or server I'm downloading from could be switched off at any time, even if i don't switch off my computer. So it could happen any time while I'm in the downloading procces... and then what happends...?


I thinc you are wrong now because... take a look here:


DOWNLOADING

Q: Why do I keep getting "Need More Sources"?

A: There are several possibilities:

1) Each Gnutella user has a limited number of slots reserved for uploads. When these slots are filled, you'll see a message that LimeWire is waiting for a certain number of "busy" clients. LimeWire will automatically retry downloads from these clients after a variable period of time in hopes that upload slots will become free. However, if the person who has the file you're trying to download has too many people requesting files, he won't be able to serve any more file requests, and your connection will be refused.

2) If the person who has the file you're trying to download has recently turned off his computer or has disconnected from the Gnutella network, you will be unable to download the file.

3) If the person who has the file you're trying to download is running inferior or buggy Gnutella software, the download could fail for any number of reasons.

4) If the person who has the file you're trying to download has since deleted the file or moved it, you may encounter problems downloading the file.

To minimize the chances of failed downloads, make your search more specific.You will have more pertinent search results from which to choose a download

http://www.limewire.com/english/content/faq.shtml#dow3

So I thinc that the program will give me the "Need More Sources" message...
More exact: the program downloads from multiple host, from files called "mirrors". And this mirrors are files with the same length and so on... (...indexes...)
Now let me understand you. You are saying that if the program can not find the file ('cose the owner's pc is off), than will try get me some other file who matches with my file at 6% or 20%... 0% ???.
This will never be a mirror file in the first place and in conclusion if I want to download a picture with a beautyful sky I could get nice porn. 'cose the head of the file could be the same at .jpg's...


the rest of your message...........
I did not understand it verry well........... sorry.....


In the end I thinc some experienced users should read the FAQ too. and there is the solution:

Q: When I try to download certain files I get a message that says "Waiting for 1s busy”. What does that message mean?

A: The "Waiting for 1s busy" message occurs when the server refuses your download because it is too overloaded. In other words, demand outstrips supply. LimeWire will continue to retry the download as long as it gets the busy signal. If you're willing to wait long enough, you'll probably get the file.

A good way to avoid this problem is to take advantage of LimeWire's "grouping" feature, which puts similar files into folders. After you search, click on the "location" column to sort results by location. Files marked "multiple (N) are available from N locations. Try downloading these files first. When you try one of these "smart" downloads, LimeWire will try all the locations one after the other, making these downloads much more likely to succeed.

Q: What is grouping?

A: Grouping is the automatic alignment of files deemed to be the same as one another based on extremely close matches of both file size and file name. Primarily used as a tool to aid in "smart downloading," grouping is an effective way for a user to ensure he has the best chance of successfully downloading a specific file.

http://www.limewire.com/english/content/faq.shtml#dow3