When trying to post comments to Reviews Module in my newly installed 7.5, I got the error message: "The html tags you attempted to use are not allowed"
I do not "attempt" to use any html tags at all, and the review is ok according to "AllowableHTML"

Anyone got a clue?

Thanxalot!

Nuke now have chatserv's protection against html code so you can insert those unless you remove them from the code.
I see in 7.5 code the only blocked html codes from $_POST are style and script and i guess you are using style so try inserting your comments without the 'style' .
cheers