Thanks Mike.
I've been looking into this for the past 2 days now with no luck. First, it turns out that the problem is not isolated to Paint.Net but appears to be specific to any .Net application.
I've downloaded and tested with 2 other applications and same issue, it appears there are are some 'system' fonts missing from my machine now so any text in any of these
applications with uses that font(s) doesn't display.
With regards Paint.Net I un-installed it completely (removed all files and registry entries) and when I go to install the new version (either 3.5.11 or 4.0) the text is not visible in the
Install dialog itself. If I select a non-English based language (like Chinese or Japanese I presume) then all the text in the Install Dialog shows up in that language correctly, other
than I can't read the languages
I've un-installed and installed all the fonts I could find as Windows 7 default fonts, I've un-installed and installed both .Net framework 4.0 and 4.5 but to no avail. If I boot in Safe mode
and I can see all the text and can install and use the applications, presumably Safe Mode uses a different font. Just not sure what is the 'default' font that Paint.Net uses for its menu
items etc so not sure what exactly is missing.