Ok so until today my Acer Iconia B1 has had no problems whatsoever with automatic screen rotation. Now though it is stuck in portrait mode and when I turn the tablet on it's side to make it turn to landscape it does nothing. No matter how many times I adjust the screen orientation settings from lock to automatic it still doesn't do anything.
I have tried a factory reset and this has not sorted the issue either.
I have checked that the accelerometor is working by downloading an app to test it and it is working fine.
How do I sort this issue out? This is really inconvenient for reading PDF files/browsing the internet and I am really dissappointed that a device that I have had for just over 4 weeks is now having problems like this.
It turned out my Iconia B1 had an issue with the motherboard. Acer sent a courier to collect it and they repaired it and had it back to me within 5 days.
I was happy, until I found out that it now has a big scratch on it that wasn't there before (like someone has taken one of those maths compasses you get in school to the back of it).
According to the UPS guy who collected it this has happened to a lot of Acer products over the years while he has worked for UPS.
For those looking at these forums doing research before buying an Acer tablet, my advice would be to go with another brand. Acer just aren't worth the hassle and their products are clearly of an inferior quality to many other brands out there (including other budget brands).