Unstable behaviour after update to 4.5

Last night I updated to 4.5. I was in the middle of a large project which I unfortunately did not remember to save a copy of before the upgrade. So now I cannot use it, even if I somehow go back to the previous version, which has been running super stable for a very long time.
I have had several crashes in a few hours and the system texts are nearly impossible to drag to a readable position because when it gets near to a tempo marking or similar, it jumps to another system and everything is jumbled around. This is extremely annoying!
Can you help me to get back to the previous version and downgrade my project file to open in the old version?
I need a stable software. If I cannot get back to the old sw, then please do some magic upgrade to the new.
This is very frustrating!

/Br Johannes Andersen