The Invasion of Albania by Serbia, say in March 1997 when various Albanian arms depots are being opened/broken into to try and cut down on arms smuggling would be the perfect casus beli for Western intervention and would make Japan's decision to strike Pearl Harbor look brilliant in comparison, which is probably why they didn't do it in OTL.
However if they decide to pull the trigger in 1997 (a move which would take an immense amount of stupidity and support from Russia), Albania's in shambles so I think they'd be able to advance fairly quickly. The only way they could really sell it would be to claim that they're trying to "restore order" in Albania by replacing Berisha's government with something more palatable and conducive to peace in the region. There's also some historical precedent for Serbia adopting pro-Christian rhetoric when interfering in Albanian affairs with the short lived Republic of Mirdita standing out as a notable example. However in spite of their relatively painless invasion and attempts to justify it, the Serbian army would quickly find itself under attack from NATO air forces and Albanian partisans. After all, in many ways the Albanian army and people had been preparing for a Yugoslavian invasion from 1945. Albanian terrain is a partisan's dream and unlike WWII, 1997 Albanians are more than willing to forego set-piece battles in favour of guerrilla warfare. Yugoslav morale would crumble faster than it did in OTL and I'd wager the fighting would be over before the end of 1997.
I'd imagine that there would be an attempt to solve Kosovo in a similar way to how it was in OTL, however TTL's situation would be even more complicated due to the situation in Albania. In OTL the unrest in 1997 brought the country to the brink of civil war. In TTL the Serbian invasion might escalate tensions even further especially if Berisha tries to rally the Albanian people around the flag in March. Such actions would play well in the North but would be disastrous in the South and would make things even worse. Add into this the fact that Greece would likely seek to intervene in such a situation to "safeguard" the Greek minority in Southern Albania. A peacekeeping mission to Southern Albania may well be necessary in TTL in addition to the one in Kosovo and may lead to the creation of a Southern Albanian state. This in turn would likely lead to Tirana experiencing a massive drop in population as the post-1992 arrivals return to the cities and villages from whence they came. If Albania is partitioned the former capital likely becomes an incredibly cool ghost town, but a ghost town nonetheless.
As Southern Albania contains most of the country's oil reserves and some of the best tourist destinations (Vlora, Saranda, Gjirokaster, Berat, the Blue Eye, etc.), it has the potential to develop quite quickly if unshackled from the Northern part of the country (IMO the South is basically the economic engine of the country as it now stands). In OTL there are plans to expand the old military airstrip outside of Saranda to facilitate tourism once the restrictions surrounding the reconstruction of Mother Teresa International Airport outside Tirana have been lifted. Without said restrictions in TTL due to a very different situation I see no reason why an airport wouldn't be constructed in TTL there or near Vlora to boost tourism. If the proper leaders can take power, Southern Albania might be able to find itself in a substantially stronger position than OTL, economically and politically. On the other hand, Northern Albania would be in even worse straits than OTL, particularly if the Catholic minority remains hostile due to the events of 1997, and would struggle to survive as an independent state. I wouldn't be surprised at all if it begins to look towards Kosovo for political and cultural leadership given the existing historical trends. These developments of course would make any kind of reunification incredibly difficult.
Serbia/Yugoslavia is an entirely different kettle of fish and would likely be just as messed up if not more.
TL;DR: A Serbian invasion of Albania in 1997 would be a colossal mistake and would likely turn the region into an even bigger mess than OTL.