Police said a bomb exploded at an intersection near a market in the southern province of Narathiwat on Monday morning, injuring at least one soldier.
Overnight, the home of a teacher in the same province, one of three near the Malaysian border plagued by violence, was burnt to the ground.
In neighbouring Yala, a school building was slightly damaged by fire, although nobody was injured, officials said.
On Sunday, while a fleet of about 50 Thai air force planes dropped paper birds as a symbol of peace on the largely Muslim region, two armed men shot dead a former prosecutor at Pattani province, police said.
The bird campaign, launched by Prime Minister Thaksin Shinawatra weeks before a general election, caught the imagination of the predominantly Buddhist country, even in Bangkok where sympathy for the Malay-speaking south is limited.
Everyone from cabinet ministers to cab drivers huddled in groups to fold cranes after Thaksin called on all 63 million Thais to make one each.
What was probably the biggest origami airdrop in history was meant to sow peace, harmony and goodwill in the region, where a decades-old insurgency that had been in hibernation, reignited in January with a raid on an army camp in which 300 assault rifles were stolen.
Thaksin's (L) bird drop comes
weeks before a general election
The mood in the three southern Malay-speaking provinces, where a low-key separatist insurgency was fought in the 70s and 80s, soured yet further in October after 85 Muslims died after a demonstration.
Most died of suffocation or were crushed in army trucks in which they had been stacked "like bricks".
The origami initiative, carried out to mark the birthday of revered King Bhumibol Adulyadej, had its critics among some Muslim leaders who said it did not gel with local culture and should not be a substitute for more traditional peace efforts.