4 way coax splitter/ amplifier too strong ?

Hi all,
I am having a problem hooking up my cable tv.
here is the scenario.
outside line goes into 2way tap/ splitter. the loss-less leg goes to cable modem , the other leg goes to 4 way splitter. from there into 4 bedrooms.
So I bought this 4 output splitter amplifier, 22db, made my ChannelMaster ( 3044) and it worked great for a few weeks.
All of a sudden, the picture went REALLY bad and snowy.
I thought the amp went bad and replaced it .
It worked again for a day or so but now it's happening again. So I am wondering :
Is the signal too strong ? how could I find out ?
What could cause it to do this after initially working fine ?

thanks for any response !!