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Ive only used Yahoo hosting once and that was years ago and it was just a basic html site, if they are not allowing special characters, spaces in file names, etc then you could have a problem hosting and type of CMS. And as far as I remember they dont have anything like cpanel I could be wrong though.
I reccomend
Surpass Hosting ive been with them for about 3 years first on a shared server now im on dedicated, there prices are fairly low and there uptime and service is very good, they also have good support too, I wouldnt dream of hosting with anyone else.
Michael Jackson = King Of Pop
Xoops = King Of CMS