I am new to Ubuntu and Linux in general. I attempted to install 12.04 on an external HDD using this tutorial, but for reasons I will skip for now, it didn't work. So I installed 12.04 onto a VirtualBox VM on OS X, and the errors ensued.
What I was originally trying to do was fix the screen resolution. It was stuck to either 800x600 or 1024x768, which is really annoying when your screen resolution is 1680x1050. Now I also would like the update manager to work correctly, consistently. It might be a bit important.
To the errors.
sudo apt-get update I get the errors/warnings:
bzip2: Data integrity error when decompressing. W: Failed to fetch bzip2: ... Hash Sum mismatch W: Failed to fetch gzip: ... Hash Sum mismatch W: Failed to fetch http://... No Hash entry in Release file ... E: Some index files failed to download. They have been ignored, or old ones used instead.
Clicking on "Check" in the update manager gives the error after attempting to update the cache:
Failed to download repository information Check your Internet connection.
Along with the same errors as
apt-get update in the details. I have also received BADSIG errors, but those are uncommon and, along with the rest, erratic depending on which server I choose.
apt-get upgrade was giving me similar errors for quite a while, but it decided to work and now it says everything is up to date, essentially. In connection with that the Update Manager finally registered the 380 updates it needed as installed.
The upgrades added 1280x960 to the list of possible resolutions, so floundering around is getting me somewhere, at least.
I have tried seemingly everything short of reinstalling VirtualBox or creating another VM and installing Ubuntu again (the latter I honestly doubt would work anyway, as this is a fresh installation). I have tried several update mirrors including the main, the US main, and the "Select Best Server" option a few times, plus some others.
In addition, I have tried the first few suggestions found in the following posts:
Higher screen resolution in VirtualBox?
What is the easiest way to resolve apt-get BADSIG GPG errors?
As well as others I have lost in the mix of the dozens of posts I have sorted through searching for an answer...
I have also seen hints that bypassing or replacing my router would fix the problem, and I tried bypassing it but for some reason my computer wouldn't successfully connect directly to the modem. So, I was unable to try that route.
Any suggestions would be wonderfully helpful, even if they are similar to the ones I have tried. Thanks in advance.
15" MacBook Pro - Late 2011
Ubuntu 12.04 on VirtualBox VM