Problems with line widths smaller that 1 pt in Illustrator CS3 in Spanish

Question

I am asking this for a friend who doesn't speak English; I don't work in Illustrator and don't even know the program. She is using Illustrator CS3 in Spanish under Windows XP Service Pack 2 also in Spanish in a machine with 4 GB RAM and 500 GB HD. As in many non English speaking countries, the decimal separator in Spanish speaking countries is the comma (,), not the point (.).
Her problem is related with applying line widths smaller that 1 pt using the dropdown list of values. Values smaller that 1 pt appear in the list with a point, not a comma, as separator: 0.25 pt, 0.50 pt and 0.75 pt instead of the expected 0,25 pt, 0,50 pt and 0,75 pt. This wouldn't matter at all; the problem is that trying to apply any of these values resuls in 1 pt wide lines. She has made a video (less than one minute) that explains the situation much better than I could do:
http://es.tinypic.com/usermedia.php?uo=AE87RzhYHCdn5HPHtpPkoA%3D%3D
Curiously, if she introduces values by hand, they are accepted in these two forms: 0,25 pt, and 1/4 pt, and applied correctly, both showing as 0,25 pt (not 0.25 pt).
Of course she can introduce values by hand every times she needs thin lines, but this is a wokaround, not a solution to her problem. Which is aggravated by the fact that she constantly has to use the thiner lines.
In desperation, she reinstalled Illustrator CS2, where the problem does not exist and everything works as expected. But she needs the new features in CS3.
I apologize if this is a known issue with a known solution, but I couldn't find anything about it in the FAQs, and after a couple of searches and wading through several pages of the topic list of this forum.

Answer 1

Back to report. I suggested to my friend to try Jacob's idea first, as it was the easier and fastest. However, I also suggested a small change, due to the following. As the dropdown list was already showing points as decimal separators, I thought it might be better not to change the language. I suggested instead to customize the settings for numbers in her chosen Spanish, changing the decimal separator from the comma to the point, and the thousands separator from the point to the comma.
She has just reported that she changed the language from Spanish to English, and then back to Spanish; and then she customized the separators as I had suggested. That did it; with this change, she can apply the smaller widths using the dropdown list, and she is so happy with her success, that she isn't going to try James's suggestion for the time being, although she may do it later on.
By the way, my friend lives in another country and we are communicating through the Forums in Spanish. This explains why communications have been very slow, and also why I don't know if she shifted from Spanish to English and back to Spainsh because this made no difference, or for some other reason. In any case, she asked me to thank very heartly Jacob and James for their help.