Well, I think I found what was causing this problem in my particular case.
On sunday, I decided to use the "more random Contacts" mod, and I tweaked some values with it, meaning that I increased the ammount of contacts of all kinds and the probability to find ships and convoys as well.
I decided to start a new career with the standard Campaign_RND.mis file and the problem of the bouncing camera is gone and working fine as it used to.
Now that I recall, this problem begun exactly the first time I used this mod.
I hope this info helps all those who have this problem, and for sure it's related to ships that are within the 50 Km range and have not been reported as contacts (visual, radar, hydrophone) yet.
CapZap