Thanks for the screenshots, Pedro. This is in fact the same exact issue that Thomas G found. So far we had found this problem in Win98 Spanish, Win98 German, and Win95 (Thomas' case). Yours is Win98 Italian, which fits the pattern of the problem: non-English, non-Japanese versions of Windows 98, and all versions of Windows 95.
Like I had said earlier, there isn't any workaround, unfortunately. I guess you'll just have to avoid using bold fonts in those OS'es. I'm sorry for the inconvenience. I wish we had caught this earlier...
- luis