When I add a pdf figure into lyx the preview works only for the current session.
When I restart Lyx I get an error: Error loading file into memory. This only
seems to occur with .pdf files (i.e. not with .svg or .png) and has no effect on
the final rendered PDF document.
I've seen references to this bug in several places online but in those case the issue was that previews were never generated. Also, I have pdf2ps and pdftoeps installed so this shouldn't be the problem either.
Running Kubuntu 12.04; Lyx 2.04

lyx -dbg graphicsand posting the output around when the error occurs. It could be a caching problem. You could also try using the Ubuntu PPA to get a development version of LyX to see if that fixes the problem: launchpad.net/~lyx-devel/+archive/daily – scottkosty Nov 3 '12 at 2:02lyx -dbg graphicsspewed tons of text which I couldn't redirect to a file usinglyx -dbg graphics > out. Of the text left on the shell screen I couldn't find anything that would be the obvious piece of information. I might try to get lyx straight from the PPA but I'm afraid of bugs. – Roey Angel Nov 3 '12 at 17:54lyx dbg graphics > out 2>&1. That will redirect both standard out and standard error to the fileout. – scottkosty Nov 3 '12 at 21:27deb http://ppa.launchpad.net/lyx-devel/daily/ubuntu quantal main deb-src http://ppa.launchpad.net/lyx-devel/daily/ubuntu quantal mainTo my resource list didn't help (I'm not getting any new version from it). Also it turns out I have the latest version from theppa:lyx-devel/release(the ubuntu repos have an older version of lyx). – Roey Angel Nov 4 '12 at 18:37sudo apt-get updatedosudo apt-get install lyx2.0(which will install what will become 2.0.5 soon) orsudo apt-get install lyx2.1(maybe less stable but maybe fixes your problem). (2) maybe try just Tools > Reconfigure. Sometimes that can solve things. (3) if nothing works, send a message to the mailing list: lyx-users@lists.lyx.org – scottkosty Nov 4 '12 at 23:43