Slash & Adler -- 1 Woman, 2 Restraining Orders

Adler alleges a woman in Oregon named Lisa Jill Martin-Cahn hired at least three private investigators since '08 to hunt him down ... "under the ruse" they were long lost lovers who met in rehab back in the early 90's.

Adler's docs, filed in L.A. County, say cops who visited Cahn at her Oregon home last month found "unopened boxes of house ware items which Cahn stated [were] wedding presents for [her and Adler's] upcoming marriage."

Now here's where Slash fits into this: He claims Cahn has contacted him and his family members -- including his mother-in-law -- by phone and letter in desperate attempts to get in touch with Adler.