So it was planned to be a very official visit by the Hungarian President into another country's territory.
It ended also as a very official ceremony, probably totally unsanctioned by the Slovak Authorities, when "Hungary's Ambassador to Slovakia Antal Heizer read out the speech Solyom was planning to deliver".
In all it was a flagrant break by Hungary regarding Diplomatic Protocol.
Not a very smart thing to do, when the Slovaks were doing all the bad things with their new Language Law. Now Hungary just look bad in the eyes of the international community, who cannot behave according to normal diplomatic rules. This Hungarian tactical mistake just give more credit to Slovak arguments that Hungary is trying to undermine Slovak Authority over its own country.
It just plays in the hands of the Slovak Nationalists.

Viking

/It just plays in the hands of the Slovak
Nationalists./

Of course, and so does Jobbik and the rest.
Read the Slovakian and the Romanian political
blogs (or YouTube debates, etc) and you will see
how all cheer up and root for Jobbik and the far
right ideology to win in Hungary and thus make the
country appear to the EU and US as a racist,
fascist, revisionist country.
Hunagry is on a self-defeating course and the
Slovakian and the Romanians are eager to help it
"succeed".
The Romanians allow Jobbik/Magyar Garda/Vona to
travel and organize themselves in Transilvania
(EMI-tabors, HVIM). They could have easily stopped
them but they won't. They want them succeed and
Hunagry lose all moral standing in the
international community.

@Viking. I seriously doubt that Solyom's office did not do things as per the book. Are you saying that's what happened? I'm told that the request to make the visit was made over a month in advance and that Slovakia waited until 2 days before the unveiling to block such; further, this is a tribute to King Stephen who reigned 100s of years ago, how would such be offensive to the international community?

To me, it sounds as though Slovakia acted strangely in making a meal of this.

Status of persona non grata is not something with which current hungarian president would be unfamiliarized. In looks a little strange pretending that this inconvenience encountered him for the first time. Not a long time ago Serbia forbidden Solyom from entrance its territory and Romania didn't allow his aircraft to land when he planned similar provocative actions in those countries. In a latter case he proved his persistency even after such strong suggestion of his unwelcomeness when he returned back after changing a plane for a car. Solyom is clearly missing that he's not behaving like a president anymore, but rather like a thief crawling into neigbour's house by a backdoor.

Rolrox,
Solyom probably told (or asked?) the Slovak Authorities he was going there to hold a speech as a private person and he did not want to meet any Slovak counterparts on the 41 year 'celebration' of the Warsaw-pact invasion of Czechoslovakia.
We can all have our opinion on how the Slovaks reacted. They probably wanted to piss Solyom off. And they succeeded.
As vdx points out, Solyom has have several 'incidents' with basically all of Hungary's neighbours, so even if I do not share vdx's conclusion, one can ask how much can a President fuck-up?
-
Then we have the interesting question which we in Hungary must ask ourself:
* Who is in charge of Foreign Policy:
- The Government, responsible for the elected Parliament, or
- The President, elected by a previous Parliament and responsible for none.
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Solyom seems to be a 'free spirit' that has another idea of what basically a ceremonial post as Hungarian President should be.