Hi Barney, thank you for your response.
Its really strange.
The files produced or compiled by textshop should be complete independently from Excel. For that reason I decided to post this issue.
Firstly I thought, maybe a bug in the MS Office software and I didn't care, but now I installed Latex and I found this issue also within the other Software (MacTex and Texshop).
I again checked MS Excel, but there is no field: "Every Number you enter by your keyboard is divided by 10".
Maybe a problem with the Number declaration inside the Lion System, for that reason I am posting this here.
Can you try logging in as a different user and see what happens.
I don't have that problem with Excel. I don't have LaTex installed on this computer, but I think I have it (and maybe TextShop) on another which I'll try when I get a chance. However, I would imagine it is something in your system that is causing the problem.
If it works when another user is logged in, then it is isolated to your user account. If still bad with the new user, then try booting into Safe Mode and see if that fixes it (hold down shift key when you restart and release it when the gray screen appears--note it takes a lot longer to boot).
If it works fine in Safe Mode, then some third-party software is affecting the system. If still bad, I'm not sure where to look. Possibly the Language and Text System Prefs under Region.