I have a test system that I just upgraded to Ubuntu 11.04 B1. General system specs are AMD Phenom II X4 940, 8 Gigs of Ram and an Nvidia GeForce 7900GS video card.
I did an online upgrade from 10.10 x64 to 11.04 x64 beta 1 without any particular issues and all my installed programs seemed to transfer OK. I did have some issues with Google Earth but I sorted those out quickly and easily enough.
I use Ed Hamrick's scanner program, VueScan Pro, for a flatbed scanner, an Epson Perfection 4490 PHOTO. Vuescan is currently at version 9.0.28, although I have seen the problems described below in 9.0.26 and 9.0.27 as well.
In order to get the scanner program to work before a native x64 bit version was released (the version 8 series was only x32), I had to run some pretty peculiar kludges swapping out 32 and 64 bit library files on the fly as the program was loading, but it worked. Since version 9 of Vuescan, there is a native x64 version that was compiled under Ubuntu 10.10 that I have been using and it runs without any of the workarounds of the old version 8 under Ubuntu 10.10.
However, something strange is happening now with Ubuntu 11.04 B1. With the Unity shell running, Vuescan 9 starts but does not display an icon for itself in the left hand Launcher bar. It queries the scanner and then just stops running (enters sleep mode). I can keep relaunching Vuescan and it just creates more zombie processes. It doesn't open its GUI window at all. I get the same symptoms if I log in to 11.04 using Ubuntu Classic or Ubuntu Classic without Compiz. But, if I log into 11.04 in Ubuntu Safe Mode, Vuescan works correctly without any problems at all.
Vuescan keeps a log and looking at this log shows no crashes or errors when it hangs. In fact I could not see any difference between the Vuescan log when it failed to open versus when it opened OK in Safe Mode log in.
It seems that something has changed 'under the hood', so to speak, with the way Ubuntu 11.04 expects to get calls to open a GUI. The vuescan program only has three files in total that it installs - an executable named "vuescan" and two support libraries named "vuescan.8ba" and "vuescan.ds" that are in the same directory as the executable. No other files are installed anywhere in the system, it is simplicity itself.
I created a desktop launcher for the program but that made no difference to the outcome except that I could drag the desktop launcher to the Unity Launch bar and have it stick there. Launching from a terminal also produces the same result. Only a Safe Mode log in allows Vuescan to run properly in Ubuntu 11.04.
So, what might Ubuntu 11.04 be looking for from this program (or conversly, what might vuescan be looking for from 11.04)? What is disabled when Ubuntu 11.04 is logged into using Safe Mode?
Any thoughts or suggestions?