Only thing you can do is check your disc's are spotlessly clean, especially make sure there are no 'fingerprints' on the silvered side. Fingerprints are the most difficult error your cd has to cope with.
Otherwise, particularly if your cd player has recently been exposed to dusty conditions, ie. decorating near by etc. The lens of the laser pick-up can be simply cleaned, very common.
CD cleaner discs with miniture brush heads are available in stores, or an engineer should clean it and not charge you too much for the job.
If it neither of those it's possibly a faulty laser pick-up or faulty spindle motor..both expensive to replace.
The cluncking noise is probably just the laser pick-up trying to focus at it's full travel and not a problem.
Cobweb, October 2004