any ETA on this?
Hi brunoe66, and welcome to Piriform.
There was improved support for Seamonkey 2.0 mentioned in the changelog of CCleaner v 2.27.1070, which is 4 versions ago.
http://filehippo.com/download_ccleaner/changelog/6780/
Not being a Seamonkey user, that's all I can tell you really, except to make sure your using a recent version of CCleaner.
There may other members using Seamonkey who can give you more definitive advice, and the devs do read these posts so your comments will be noted.
Hope that helps.