Hi -I have lot's of trouble trying to get a consistent, clean transition in CS5. Mulple systems, multple configs but here is an example of the latest.
Quadro FX 5800
12 GB RAM
2 x 6core XEON (X5680)
Atto R380 RAID controller
CalDigit HDOne Storage
1. place title with a transparent drop shadow, fade in, the fade won't be smooth. it will 'pop' at the end of the transition - the fade is smooth until the very end, and then jumps to opaque (or whatever opacity level is set for title/graphic)
Rendering makes little difference, and in the case of the video behind it can sometimes result in additional blooming, jumping in opacity levels and so on. For example if I have a cross dissolve from black on video clip, it will preview fine, but after rendering we will get color shifts, or opacity jumps instead of a smooth fade in.
Changing from GPU to software will clear the video previews to resolve the rendered area problems, but then we are just back at unsmooth transitions of titles and so on.
Have changed various rendering settings, codecs etc...