Maxi Fuse 5

I have a Saab 9-3 convertible (1998). The Maxi fuse (number 5), has blown. I fitted a new fuse, started the car for a few seconds, and checked the fuse to find it was again blown. I have found that this fuse is in connection to the roof. I have had the roof motor checked at a local garage to be ok. I have also checked the hydraulic fluid to be fine and also manually put the roof down and back up to check the roof mechanism. All ok! I am now not sure why this fuse blows, especially as I don’t need to work the roof to blow the fuse. I only need to start the car to blow this fuse. I am now thinking that it is not the roof that is causing the fuse to blow? Is there a way I can find out what the problem is? Are there any other checks I can do that are on the Maxi fuse 5 circuit, that may case this problem? Please, can anyone advise me?

Many thanks Mike...