Hello,
I see a lot of software installed on your PC.
Siemens + Windows = Sindows, that doesn't like many other software packages sometimes. WinCC Flex 2008 uses SQL Server 2005 if I remember well, have you installed something recently that conflicts with the database... maybe an SQL Server 2008 ?
Can you do a PC recovery to the moment where WinCC Flex still worked ?
I personally prefer to install Siemens software on a VM seperated from other automation software brands.
Kind regards,
C