I bought my Samsung Galaxy S Plus GT i9001 a couple of months ago.
I have been facing this issue of the phone lag (a little) and at times completely freezing, causing the phone to restart on its own. When the phone is restarting the colors on startup screen(samsung logo) appear dark/dull. After startup the phone speaker stops working.
I tried toggling between silent and non silent modes to check if the speaker works but it doesn't help.The only way to fix this is to manually restart the phone.
The problem doesn't occur very frequently but does happen may be once a weeks. I tried factory resetting the phone once, but the problem came back in sometime.
I checked with a few of my friends with an S plus and non of them are facing any sort of lag or freezing issues. I seem to be the only one having the problem.
Is there anyone here who has faced this or a similar problem? I am suspecting a firmware problem.
UPDATE: The problem with the speaker was just happened a few time. But the phone restarts frequently approx. every 3 days.