Hi, Chrissie,
Yes, I definitely believe past-life experiences can cause present-day phobias. I know first-hand!
In my most-remembered past life, the one most connected with this one, I died a very traumatic death, surrounded by crowds pressing in around me and screaming their hatred at me. For years before this, I was kept a prisoner by these crowds, fearing every day that they might break in and hurt me, or worse, hurt my husband, my sister or my children. Large amounts of people equaled great danger in my mind, and unfortunately, it still does.
I suffer from agoraphobia, a crippling fear of unfamiliar places, people and situations, and most especially crowds. I have to have a family member right by my side whenever I leave my house, and though I can sometimes go into a store or somehwere alone, it can't be for long, and if it's crowded, I go into a panic attack and end up huddling under my pillows, crying. I'm working on it, and it really helped me to understand where this fear came from.
Good question, and a very important one, I think.