New Memory Issues ??

About a week ago,I installed some new ram in a Presario CQ 57-229WM.I removed (1) one gb stick out of two and replaced it with a 4 gb stick for a total of five.Upon reboots my pc began giving me error messages such as a "hardware problem" within the memory and that my drive needed to be scanned for errors.Windows mem diagnostics told me nothing other than there being a hardware problem.Dskchk found no errors.Next,I ran Malwarebyytes.Malwarebytes found a few (46) "pups" (whatever those exactly are) and quarantined them.Next,I ran an Avast boot scan.Avast found some issues with Java (which Firefox had turned off months ago) and quarantined them.Now,Firefox seems to be crashing A LOT on that pc.In fact,as I was writing this (before) the entire pc crashed.Needless to say-I am on another pc writing this.I am at wits end.I was going to try using my Eusing registry cleaner but,it won't update ! And,just for your info...I have not tried booting either Windows or Firefox in safe mode (don't know what good that would do me,really).I have written the person who sold me the memory (through ebay) but,that was on Fri.So,I haven't heard anything from him yet.Does ANYONE have any ideas ? Before I purchased this memory,I made certain that it was compatible (at least I thought I had). My next idea,is to remove the new memory and put the old (2) one gb sticks back in Anyone ????????????

Try running with only one RAM stick, either the new 4GB or one of the 1GB. It is always best to replace RAM in matched pairs for performance and compatibility.

Run this RAM test:

RAM (memory) test:

This will require memtest on a bootable CD or USB stick.
RAM - Test with Memtest86+

It may take a few hours to do a full 8 passes.

Unless you have a specific need for Java, I'd leave it off the machine.
PUPs are Potentially Unwanted Programs, thing usually bundled with downloads which should have a check mark for opting out. For example, Adobe updates sometime have Goggle Chrome or McAfee security included.

Crap, I should have mentioned DO NOT use any registry cleaners other than the one in CCleaner. Most 3rd party ones are far too aggressive. Link in my sig for CCleaner if you don't have it.

Just start memtest before going to bed or to work and let it run, no harm if it runs a long time. Follow the instructions it the tutorial I linked to.