Virtualbox freezes when opening two virtual machines

[scottgus1]

Mpack suggested the tweaks for memory and core count, essentially trying for the point where all three OS's could hopefully fit without starving each other.

Much of sizing a computer for multiple guests is adding the individual guest needs and the host:
Memory for each guest + host's typical nothing-else-running usage <= total host memory.
Cores for each guest + one for the host <= total host cores (not hyperthreads) <-there's wiggle room on this one, not all OS's use all cores all the time. If they all do, stability tanks.
Drives depend on the drive type: if a platter drive, no more than two modern OS's on one platter drive (personal experience). If SSD, fill that sucker up!

A four-core I5 no hyperthreads or i7 with hyperthreads, SSD drive, and 8GB memory could handle both your guests easily, and maybe one more.

[joethemango]

Hi Scott,

Please close this case if ever you have an open one. I guess the problem is resolved.
I have upgraded my RAM from 4 GB to 8 GB and i can now run three OS including the host with no problem.

Things seems to be running smoothly as of this writing.

Thanks for the help!

[scottgus1]

Nice! more memory does help. Glad you're up and running!

[joethemango]

thanks for your help mate!i can confirm that my virtual box is running smoothly for days now with no known issues!