Looks like a corrupted registry. Try fixing your registry using following method and check.
Close SolidWorks and got to Start > Run > type regedit > go to HKEY_CURRENT_USER > Software > SolidWorks > SolidWorks 2009
I got the same problem on twice PC.
I was about to update Solidworks them a got a message in the installer asking me to check this page : https://www.solidworks.com/sw/support/TechKB3072630.htm
I have followed their recommandation and it looks I haven't got any issues since my update. I got some every 15min or more before.
I had the same problem with SW 2015 on Win7 64bit and none of the above mentioned advices worked for me. Then I read this thread SW2009 64bit englisch -> auf deutsch umstellen (DS SolidWorks/SolidWorks) - Foren auf CAD.de
and now no warning message pop up. I have simply change the format language in Regional and language options back to English.
Changing the language settings seemed to work for me as well. Thank you!
I've reinstalled Solidworks Choosing my system language as well as English. I didn't need Polish version, so I just unchecked it, but it turns out, that for some reason Solidworks is trying to find sldresu.dll in the Polish language location in the installation folder. Since I haven't installed Polish version, the folder was empty. My Windows is set to Polish, maybe that's why.
Anyway, I fired up the installer again, chosen the Polish language pack to be installed too and everything works fine. Then I've chosen to use English Menys and commands in Solidworks Options.
Hope it helps.
I made a junction link to 'SOLIDWORKS\SOLIDWORKS\lang\english' to 'SOLIDWORKS\SOLIDWORKS\lang\turkish' and it solved the problem.
You can use the junction link utility from the link belove;
right click on english directory + drug & drop in same lang folder and change the name to your own lang.
And now you don't have to disable preview and no error message.
I had the same problem for my sw 2016 and i already fixed it, i just went to:
C:\Program Files\SOLIDWORKS Corp\SOLIDWORKS\lang
I searched the file sldresu.dll in that route and in my case the system found the file in a different folder (i have the spanish version installed) but the file was in the english folder so i just copied the file from the search and i went to C:\Program Files\SOLIDWORKS Corp\SOLIDWORKS\lang\spanish i pasted the file in this route because the version i have i restarted my pc and the problem was solved my solidworks is working perfectly again.
I hope you guys can solve the problem in the same way.