Due to security in the 3rd Edition of S60, applications must be signed before they can be installed. Although most commercial programmes
are already signed, there is a lot of useful freeware where that still must be done for the particular IMEI.

Manual:

First download the necessary software:

1. Enter
http://rapidshare.com/files/34806908/SignSIS-GUI_v1.1.exe.html in the web browser.

2. Click on the “Free” Button.

3. Wait until the download is ready.

4. Choose a download provider.

5. Enter the security code and choose “Download via…”.

Signing S60v3 files- Easiest way possible!![Tutorial]
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FAQ's:

All Signing Issues Here Only!

Here you will find all the Related Query/Tutorials/Help|FAQ*|{ by me} for Signing S60v3 files.
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Which Files to Sign?
The applications posted with the Title in this section with "Unsigned" tag Must be Signed in order to get it working on Individual OS 9.1 devices.

Signing of Files Completely Depends on IMEI of your Phone, in that case if you want to use unsigned file, you must sign it with your IMEI and get it working.

Why is it Really Necessary to Sign Files?

about Device start-up failed for n-gage

here' the tip

1.App closed main error
- run any explorer ( seleQ, Fexplorer, fileman)
- GO TO C:\system\bootdata
- DELETE: FirstBoot.dat
- turn off the phone and TAKE OUT THE MMC!!
- switch on phone(if u everything do right u will probably need to type in time and date)
- switch off phone again
- put in MMC back
- switch ON phone and..
NO MORE ERROR!!