Finally Fix ia32-libs depends error

I'm using Ubuntu 12.04 at work, the laptop is a intel + nvidia video card, so I have tried a lot of solution to fix the 3D issue, but I finally found it introduce a lot of other issue like ia32-libs depends issue.

The log is like this:

/var@jasozhang-nv $ sudo apt-get install ia32-libs
Reading package lists... Done
Building dependency tree       
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
 ia32-libs : Depends: ia32-libs-multiarch
E: Unable to correct problems, you have held broken packages.

After tried every method on google, all failed.

So I remember I have add lots of ppa which maybe related to this issue.

I tried this:

1. in Update Manager -> Software Sources -> Other Software
Enable *ALL* ppa you have ever installed, what even currently it was disable or not, enable them all.

2. Then, install y-ppa-manager, (method can be search on google).
*Purge* Every ppa you have.

After did this, the package relationship become a normal.

In the end, I think this is a lesson that install ppa, specially big ppa, like xorg-edgers, kubuntu-ppa are very risky. Be caution when you install such ppa.