One of the most common problems when installing a program on a Symbian OS device are certification errors. These basically occur due to the expiration of a program's digital signature and the fact that Nokia has revoked the licence that is distributed to developers.

If you're experiencing this annoying problem on a regular basis and want to remedy the situation then you could do a lot worse than installing Mobile Signer on your Nokia phone. This free program represents an interesting solution that means you don't need to hack your phone files whenever a digital signature has expired.

Through a pretty straightforward user interface, the software allows you to renew the signing of the programs directly from your own phone. I say straightforward because it is, once you know what all of the input fields are for.

Luckily, there's plenty of information on the developer's site, so you can learn the ins and outs of Mobile Signer pretty quickly. The program is pretty well laid-out though and it won't take you long to whisk through all of the various menus and options locked within it.

If you're blighted by programs that won't install due to expired digital signatures then Mobile Signer represents a useful solution.