Why is it so difficult to find a topic for my thesis research? I've majored in computer science (BSc: close to MIS, MSc: advanced software engineering), I've worked on dissertations on totally different topics in every stage at college, now I'm planning to do a PhD and I've been looking at different topics from various sub-fields but I frankly can't pin one to use as a starting point. I would say that I like X topic or Y and when I look closer at the papers being published in the field they seem too obscure to me and I can barely comprehend their abstracts. For example, I was searching for starting point in solving concurrency problems in software or even advance such technique since I felt it's what I want to do and what I know that would keep me motivated but I frankly couldn't find anything, I've looked at publications that reference famous papers/book (things I've researched very briefly) like communicating sequential processes and cooperating sequential processes but there was nothing that could give me a good start.

My questions here, am I looking in the wrong sub-field? I know I'm highly motivated by the previously mentioned area but do I understand enough to enter such area? I've seen people jump from psychology to computer science at PhD level and I wonder how someone could do such thing. Also am I even a PhD material if I can't pass this stage?

Note: the topics of my past dissertations were on AI and online social communities
Your supervisor or potential supervisors should be able to help - and I don't necessarily mean by talking to them.  First of all identify potential supervisors whose (recent) work you like and (mostly) understand. In the first instance look at their recent papers, and particularly concentrate on any points they raise in discussion or future work.  In particular do a SWOT analysis and note what are the best and worst features of the approaches, and whether you can see opportunities for different, even interdisciplinary, work to be brought to bear.

To the extent you don't understand anything, don't keep reading and rereading and struggling with it, go back to the earlier work and the citations.  Try go be back to the originators of the concepts you are lacking or find difficult, and the commentators who clarify the insights behind the formalisms.  Look for conference and workshop papers for these early developmental versions of work, rather than the erudite and impenetrable journal versions.