Two security bulletins have been updated today, they will give you a reason more to install IF 2 for IBM Notes 9.0.1 Fixpack 5 on Windows.
small update: installing the IBM Notes 64-bit 9.0.1 IF1 (for Mac) caused some issues.. I was not able to launch IBM Notes anymore, installing the IF1 again would launch an error that “the fix was only for the 64bit client” and therefore would not run. I ran the install for the 9.0.1 64-bit client again which fixed the problem and now the «About IBM Notes» shows:
Release 9.0.1 (64-bit) SHF619
FP/IF nightmare all over again or only a local issue?