CD-ROM Misalignment

[nag]

My Samsung 32x CDROM is giving problems for some time.It couldn't read cd's.Whenever I send it to technical person,he said it was laser misalignment and fixed it.It has happened three times and again it is having same problem.
How this misalignment occur and how can I fix(If I can?) or prevent it?
Any Info or links would be helpful?
Thanx.

[canit]

Sounds like a lemon to me. Return it and get your mony back.