When you have a Hot Fix installed in your server it is required that you remove the Hot Fix bfory you are permitted to install the Fix Pack.  The reason fo  this is that the code in the Hot Fix hs not beed thourghly quality control tested, and is not available for public release.  Since the code is not availble for public release, it will not be incorporate as part of an official Fix Pack.  As stated previously, if you run he Hot Fix installer on your server, you can remove the Hot Fix.  Then you will be able to install the Fix Pack.  The only other way to upgrade thisserver would be to install the Base Version (i.e. 9.0.1) and then install the FixPack.  By installing the Base Version, you are overwriting the code which was installed by theFix Pack.